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Long-term Outcome after Corneal Transplantation
Long-term Outcome after Corneal Transplantation Visual Result and Patient Perception of Success K. A. WILLIAMS, PhD, J. K. ASH, BSc(Hons), P. PARARAJASEGARAM, FRCS, S. HARRIS, Dipl 0, D. J. COSTER, FRACO
Abstract: Snellen acuity, reading line, and keratometry were measured in a cohort of 60 patients at 2 or more years after penetrating keratoplasty was performed. Patients were asked to complete a questionnaire to elicit information on their perceptions of visual function and the success of the procedure. Using preferred correction, a Snellen acuity of 6/18 or better was achieved by 65%, and a reading line of N8 or better was achieved by 57% of index grafts. Thirtyeight percent had more than 5 diopters (D) of astigmatism in the graft. Approximately 75% of patients reported satisfaction with their graft (satisfaction being associated with better acuity in the grafted eye than the other eye), graft clarity, and a perceived improvement in lifestyle. Dissatisfaction appeared to be associated with graft failure and problems with contact lens wear. The findings have implications for patient selection for corneal transplantation and for the measurement of outcome. Ophthalmology 1991; 98:651-657
Corneal transplantation is generally considered to be a very successful procedure. However, published studies of long-term visual outcome in cohorts of patients with mixed indications for graft are surprisingly few. 1,2 Outcome may be measured in various ways, with the criteria for success depending primarily on the indication for the surgery. Corneal grafts are most frequently performed for the improvement of visual acuity but may also be performed for the relief of pain or for maintenance of the structural integrity of the globe. The optical outcome after penetrating keratoplasty, as measured by conventional indices such as graft clarity Originally received: November 5, 1990. Revision accepted: January 14, 1991. From the Department of Ophthalmology, Flinders University of South Australia, Adelaide. Supported by Flinders Medical Centre Research Foundation, the Pank Ophthalmic Trust, and the NH & MRC (grant 890858). Reprint requests to K. A. Williams, PhD, Department of Ophthalmology, Flinders Medical Centre, Bedford Park SA 5042, Australia.
and keratometry, does not always parallel the visual out-
come,' and occasionally neither observed optical nor vi-
sual result seems to match the patients' own perceptions of the apparent degree of success of the procedure. It is not always clear whether such disparities reflect unrealistic expectations on the part of the patient, inadequate pregraft counseling, or unrecognized factors affecting visual rehabilitation, whether physiological or social. We are not aware of any systematic study of corneal graft recipients' assessments of the benefits of their surgery, nor of any attempt to correlate objective measures of visual outcome with patients' subjective perceptions of the result. Our approach was to measure Snellen acuity, reading acuity, and astigmatism in both eyes of a substantial cohort of patients at 2 or more years postgraft. All patients had been treated in a single center by the same surgeon and had received consistent follow-up. We reasoned that by 2 years postkeratoplasty, all graft sutures were likely to have been removed, all refractive surgery on the grafted eye completed, any factors affecting visual result that were essentially unconnected with the actual graft would have been dealt with or would have stabilized, and a reasonably 651
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Table 1. Indication for Graft in the Interviewed Population Indication for Graft Keratoconus Failed previous graft HSV keratitis inactive with corneal scar active] HZO (inactive with corneal scar) Aphakic bullous keratopathy Corneal scart Interstitial keratitis§ Lipid keratopathy'' Fuchs' dystrophy
No. Patients
29
Percent
48
9*
15
4
12
3 1 5 4
2 2
1
2 8 7 3 3 2
HSV = herpes simplex virus; HZO = herpes zoster ophthalmicus. * One case with bacterial superinfection. t Two cases with impending perforation; 1 case with bacterial superinfection. t Two cases with old traumatic injury. § One case luetic, 1 case old trachoma. II One case with recurrent ulceration.
stable refraction should have been achieved. A number of objective measures of visual outcome were then determined, and the patients' feelings about the graft, their perceptions of any changes resulting from the graft, their estimation of the overall success of the procedure, and the extent to which their prior expectations had been met were assessed by means of a questionnaire.
MATERIALS AND METHODS PATIENTS
The beginning patient population consisted of 209 consecutive recipients of a penetrating corneal graft who had undergone their keratoplasty procedure at least 24 months before the start of the study. Seventy-seven patients were excluded at the outset because of death in the intervening period, known serious illness (including dementia), residence at a distance of more than 500 km from the study center, or graft failure followed by recent regraft (with less than 24 months subsequent follow-up). Graft failure alone was not an exclusion criterion. The remaining 132patients were invited to interview. Of these, 41 patients refused to participate or failed to reply, 31 expressed willingness to participate but were unable to travel to the clinic during the time set aside for the study, and 60 attended for interview, were assessed, and completed a questionnaire. These 60 formed the interviewed study population. Informed consent for the study was requested and obtained from all patients. STRUCTURED INTERVIEW
Assessment of visual outcome and patient perception of outcome were determined in a structured interview. All interviews were conducted by the same individual, 652
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who was totally unconnected with the eye clinic and was not involved in any aspect of the care of eye patients. In each case, the interviewer stressed past and continuing independence from the eye care team and assured the patient that the responses to the questionnaire would be kept confidential. Objective measures of visual outcome were then taken and the patient was guided through the questionnaire by the interviewer. An interpreter was called in when necessary. For the one patient younger than 10 years of age, the questionnaire was answered by the child's mother. QUESTIONNAIRE
The questionnaire, validated during a pilot project, contained 24 questions with predominantly either/or responses, together with provision for patients' comments. Questions related to satisfaction with prescribed correction and counseling, and perceptions of visual outcome in terms of function (ability to work and perform tasks of daily living), cosmesis, relief of pain, and prior expectations. MEASUREMENTS OF VISUAL ACUITY AND FUNCTION
Snellen acuity, reading line, and keratometry readings were measured for each eye independently, using the preferred correction. The preferred correction was defined as the method of correction (spectacles or contact lens or neither) currently in daily use by the patient, irrespective of whether that correction had been prescribed by the consultant ophthalmologist. Uncorrected Snellen acuity and acuity with pinhole also were measured. All measurements were made under the same conditions of ambient illumination. Where a decision was made as to the better eye and no difference was measurable between the two eyes, the grafted eye was counted as the better eye. STATISTICAL ANALYSIS
Chi-square contingency table tests with continuity correction were used to test associations with patient satisfaction. For two by two tables in which there were fewer than 5 observations per cell, the Fisher's exact test was employed.
RESULTS INTERVIEWED STUDY POPULATION
For the 60 patients who were interviewed, follow-up ranged from 2.2 to 9.1 years (mean, 4.9 years). All grafts had been performed by the one surgeon between 1980 and 1987. Recipient age at graft varied from 2 to 81 years (mean, 42 years). Indications for graft in the index eye are presented in Table 1. In this series, 50 (83%) patients were grafted in an attempt to improve visual acuity, 4 (7%) patients were grafted to maintain the integrity of the eye, and 6 (l 0%) received a graft primarily for the relief
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K READINGS IN GRAFT
of pain but also in the expectation of improved visual outcome. Twenty-three percent had bilateral corneal grafts, and, in these patients, the index graft was chosen as the graft with the longer period of follow-up. Fiftythree percent of recipients were working or studying and 47% were home-based or retired. COMPARISON BETWEEN INTERVIEWED AND NONINTERVIEWED POPULATIONS
The interviewed study population was compared both with the total cohort and with the 132 patients invited to interview, with respect to sex, age at graft, calender year of graft, and indication for graft, and was found not to differ significantly from either (P > 0.05, chi-square test). In particular, keratoconus and failed previous grafts were the commonest indications for graft, while pseudophakic bullous keratopathy was rare (n = 2 overall). Additional confounding influences might include variations in graft clarity and in visual acuity. The interviewed population (n = 60) was accordingly compared with the patients (n = 72) invited for interview but who did not attend. Graft clarity and Snellen acuity in the latter group were determined from the notes, using the data recorded at the last time offollow-up. The lengths oftime from graft to followup and from the time of last follow-up to the date of analysis in this group were quite variable, but whereas 8 of 60 grafts had failed in the interviewed group, 22 of 72 grafts were recorded as having failed in the group that did not attend (P < 0.05, chi-square test). Snellen acuities in the noninterviewed population had not been recorded for 11 % and the remainder were a mixture of uncorrected and best-corrected values; however, 38% of the total had achieved a visual acuity of 6/18 or better in the grafted eye, which is not as good as in the interviewed population (see below). Therefore, we were unable to separate the interviewed group from the invited but not interviewed group on the basis of preoperative factors, but the available evidence suggests that the latter group have, in fact, fared less well since the graft. OBJECTIVE MEASURES OF VISUAL OUTCOME: INTERVIEWED POPULATION
The optical status of the graft was determined by graft clarity and keratometry. Graft clarity. Eight index grafts (13%) had failed (4 cases of irreversible rejection, 2 of which were complicated by glaucoma, 1 case each of corneal decompensation in an aphake, epithelial downgrowth, traumatic rupture, and recurrent herpetic infection). Keratometry. Keratometry readings were used to determine the degree of residual astigmatism (Fig 1).Thirtyeight percent of patients had greater than 5 diopters (D) of astigmatism or irregular mires in the grafted eye and 9 patients (15%), all with keratoconus, had greater than 5 D of astigmatism in both eyes. Refractive surgery postgraft had been performed on 8 patients (5 relaxing incisions, 1 relaxing incisions plus wedge resection, and 2 adjustment of graft sutures).
15 , . . - - - - - - - - - - - - - - - ,
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Fig 1. Keratometry readings (in diopters) in the grafted eye. 1M = irregular mires.
Visual function was assessedby means of Snellen acuity and reading line measurements and by prescribed correction. Visual acuity. Snellen acuity at 2 or more years after graft in the grafted eye, the other eye, and the better of the two eyes, measured with the preferred correction in each case, is shown in Figure 2. Using the preferred correction, a visual acuity of 6/18 or better was achieved by 65% of recipients in the grafted eye, by 78% in the other eye, and by 92% in the better of the two eyes. Reading ability. Reading line for the graft, the other eye, and for the better eye, measured with preferred correction in each case, is shown in Figure 3. A reading line of N8 or better was achieved by 57% of patients in the grafted eye, by 57% in the other eye, and by 67% in the better of the two eyes. Prescribed correction. Fifty-two percent of patients had been prescribed spectacles, 17% had been prescribed contact lenses, 20% had both spectacles and contact lenses, and 11 % required no correction. VISUAL BEHAVIOR AND PATIENT SATISFACTION
Visual behavior and patient satisfaction were measured with the questionnaire. Visual behavior. Patient responses to the questionnaire are summarized in Tables 2 through 6. Approximately 75% of graft recipients reported that they were managing the tasks of daily living quite successfully (Table 2). However, some patients commented that their capacity to function adequately depended on the level of ambient light. A major difficulty appeared to be with reading fine print, but, nevertheless, 73% of patients reported that they 653
SNELLEN ACUITY
READING LINE: GRAFT
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en
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Fig 2. Snellen acuity in the graft. the other eye, and the better eye, measured with preferred correction. CF = cou nt fingers at I mete r, HM = hand motion; LP = light perceptio n; NLP = no light perception.
654
20
N4.5 N5
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READING LINE Fig 3. Readi ng line in the grafted eye, the oth er eye, and the better eye, measured with preferred correction. NR = not recorded/not measurable.
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Table 2. Questionnaire Responses: Activities of Daily Living Question
Yes
Can you manage your hobbies and leisure activities? Can you read whatever you want to read? Do you drive a car? Can you recognize peoples' faces most of the time? Can you move unaided in unfamiliar surroundings? Does your vision restrict you in your daily living:
77% 73% 63% 80% 82% 40%
No
Table 3. Questionnaire Responses: Perceptions of Postoperative Changes
N/A*
23% 27% 20% 17% 20% 18% 60%
* N/A = not applicable (e.g., patient had never learned to drive orhad no access to a car).
could read whatever they wished. Forty percent of patients believed that their overall vision restricted desired activities, especially leisure activities of which they had once been capable. Such activities included flying an airplane, playing golf, contact sports, tennis, lawn bowling, sewing, and gardening. Approximately 66% of recipients believed that their vision had improved as a result of the graft, 33% believed that their ability to work or study had improved, and approximately 50% believed that their lifestyle had improved (Table 3). However, approximately 25% ofpatients believed that their counseling, before graft placement, had been inadequate and 10 to 13% reported that they had not been told of the possibilities of graft failure, of less than perfect vision, or the probable need for glasses or contact lenses postoperatively (Table 4). The clinical staff involved were unequivocal in their certainty that all patients without exception had been carefully and appropriately counseled. We considered that perhaps those patients who had required emergency grafts (ofwhom there were four), might not have been counseled because of lack of time. However, 3 of these 4 patients considered that they had been well counseled. The fourth patient spoke poor English and it was not possible to establish whether effective communication had been established at the time of graft placement. Although the majority of patients believed that their graft had been worthwhile and were of the opinion that they would make the same decision (to have the graft) again, less than half believed that the outcome had matched their pregraft expectations (Table 5). This discrepancy seemed to be related neither to the incidence or severity of postoperative complications (approximately a third of recipients reported more complications than expected, a third reported fewer than expected, and a third reported as many as expected) nor to a perceived lack of counseling, but rather to a natural (if unrealistic) hope that all would be well, as evinced by the comments made at the interview. Eighty-six percent of patients who were prescribed spectacles and 50% of those who were prescribed contact lenses reported that they disliked wearing their prescribed correction. Of the recipients prescribed spectacles or contact lenses, most (89%) did actually use them. However, not all patients who reported that they used their spectacles or contact lenses in daily living (preferred correction) were necessarily happy with them.
Question
Yes
No
No change or uncertain
Since your graft and as a result of your grafl: Has your vision improved? Has your ability to work improved? Has your social life improved? Has your appearance improved? Has your lifestyle improved?
67% 38% 22% 8% 52%
7% 8% 7%
32% 55% 70% 85% 47%
Table 4. Questionnaire Responses: Pregraft Counseling Question
Yes
No*
Were you appropriately counseled before graft? Were you told your graft might fail? Were you told your vision might not be perfect? Were you told you might need glasses or contact lenses?
75% 82%
23% 10%
83%
13%
80%
13%
* Replies do not add up to 100% across rows because some patients were uncertain or were unable to remember. Table 5. Questionnaire Responses: Patient Expectation and Satisfaction Question
Yes
No
Uncertain or N/A
Are you happy with your graft outcome? Does the outcome match your expectations? Would you make the same decision (to have a graft) again? Was having the graft worthwhile? Have you had more complications than you expected, since graft? Overall, are you very happy with your graft?
80% 47%
20% 45%
8%
87% 93%
13% 3%
3%
28% 70%
70%* 10%
20%
N/A = not applicable. * 30% had fewer than expected. Table 6. Patient Satisfaction and Snellen Acuity in the Belter Eye Patient Satisfaction
Snellen Acuity Belter in: Other Eye Graft*
Total
Patient satisfied Patient dissatisfied
27 4
18 11
45 15
Total
31
29
60
* Where best-corrected acuities in each eye were the same, the graft was counted as the better eye. P = 0.037 (Fisher's exact probability test).
Patient satisfaction. Overall patient satisfaction was assessed on the basis of the answers to what was essentially the same question, repeated twice, once near the beginning of the questionnaire and once close to the end. Satisfied patients were defined as those giving positive responses 655
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to these questions, dissatisfied patients as those giving negative responses, and patients with mixed feelings as those giving discordant responses. Patients with mixed or ambivalent feelings were included with the dissatisfied patients. Ofthe sixgrafts performed for reliefof pain, fivepatients (all with surviving grafts) were pleased with their graft outcome; one, whose graft had failed, was dissatisfied. Of the four grafts performed for structural repair, three patients (two with surviving grafts, one with a failed graft) were satisfied with the outcome, whereas one patient (with a failed graft) was dissatisfied. Of the 50 grafts performed for improvement in visual function , 37 patients professed to be satisfied (35 with clear grafts, 2 with failed grafts) and 13 were unhappy (10 with clear grafts, 3 with failed grafts). A significant association was found between graft outcome (i.e., graft clarity) and recipient satisfaction (P < 0.02, Fisher's exact test). No significant association (corrected P > 0.05, chisquare test) was found between patient satisfaction and a specific level of Snellen acuity using preferred correction (levels tested: better or equal to 6/6, 6/12 , 6/18, 6/60) . However, a significant association was found between patient satisfaction and better Snellen acuity (with preferred correction) in the grafted eye than in the other eye (Table 6; P < 0.05, Fisher's exact test). No association was noted between satisfaction and the presence or absence of more than 5 D of astigmatism or irregular mires in the grafted eye or patient age at graft. Answers to all the questions concerning activities of daily living, perceptions of postoperative changes, pregraft counseling, expectations, and satisfaction with the method of correction were tested individually against patient satisfaction. No correlation was found between answers to most questions and satisfaction. Satisfied patients were more likely to report an improved ability to work or study, a perceived improvement in lifestyle, and that their preoperative expectations had been met, but, of these, only the association with reported improved lifestyle reached significance (P < 0.002, Fisher's exact test). Of the 15 patients expressing a degree ofdissatisfaction with their corneal graft, 8 reported substantial unhappiness, as assessed by negative responses to the questions relating to satisfaction with the graft and provision of additional , unsolicited comments to the effect that they were very unhappy. No one factor stood out to mark these 8 patients. Three patients had failed grafts. In the other five patients, Snellen acuities in the graft (with preferred correction) were 6/6 , 6/9, 6/9 , 6/12, and counting fingers at 1 meter, and astigmatism 3.6,4.6, 11.4, 12, and over 8 D, respectively. These five patients all reported difficulty with contact lens wear, and, indeed , this factor appeared to be a major source of unhappiness with the grafts. PATIENT COMMENTS
The opportunity for patients to provide additional, unsolicited information was provided at the end of each structured interview. Among the most commonly proffered comments were that glare was a continuing problem and that driving at night was difficult; that the constantly 656
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changing refraction in the first year or so after graft was unexpected, annoying, and expensi ve; and that before graft placement, it would have been a help to have been able to talk to someone else who had already undergone corneal transplantation. Some patients commented that they had been unable to absorb all the information given to them in the clinic, but that the y were too embarrassed or diffident to seek further clarification.
DISCUSSION An important determinant of corneal graft outcome is the time after graft placement at which measurements are taken. In assessments of the risk factors associated with overall corneal graft survival, life table analyses allow survival probabilities to be plotted as a function of time postgraft. 1,4-6 Measurements of visual outcome, however, are generally made at one or more specific time points, although it is generally accepted that such measurements alter with time. 2 •7 We chose to examine visual outcome and patient satisfaction at 2 or more years postoperatively, at a time when the constantly changing refraction associated with the early postkeratoplasty period " and with the removal of graft sutures? had stabilized. A decision was made at the outset of this study to use patient-preferred correction (sometimes called social correction) in the measurements of Snellen acuity and reading line, to obtain accurate measures of actual visual functioning. Using the preferred correction, a Snellen acuity of 6/ 18 or better was achieved by 65% and a reading line of N8 or better was achieved by 57% of index grafts. The question of stereopsis was not specifically addressed, although this would be a useful measure in further studies. Visual outcome is a function of the person, rather than the grafted eye: considering the better of the two eyes, 92% of the cohort achieved a Snellen acuity of 6/18 or better and 67% were able to read N8 or better. Thus, the group as a whole did not appear to be particularly visually disabled. However, it was noteworthy that 20 to 30% of patients expressed some degree of disappointment with the outcome of their grafts, with 13% being extremely dissatisfied, and that 40% considered that their overall vision (assessed as a function of both eyes) restricted them in daily living. Of some interest was the almost universally expressed comment that glare remained a problem in the grafted eye. Some loss of visual function has previously been reported in the presence of glare. 10 Unexpectedly, satisfaction was not associated with the achievement of a specific, high level of measured acuity in the grafted eye, but rather with achievement of a better Snellen acuity (at any level) in the grafted eye than in the other eye. Some patients with quite poor Snellen acuity in their grafted eye, nonetheless reported that they were very pleased with the outcome. This finding may have some ramifications for patient selection for corneal transplantation, given the general shortfall in corneal donor material. Where material is limited, it may be appropriate to consider the status of the other eye and to refrain from surgery if it is believed that a better visual result in the
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eye under consideration for graft cannot readily be achieved. However, achievement of navigable vision in the grafted eye may be of benefit to the patient with even poorer visual function in the other eye. A further consideration relates to the patient's willingness to wear contact lenses postoperatively, given that problems with lens wear appeared to be associated with dissatisfaction, irrespective of the visual result obtained with the graft. Not surprisingly, dissatisfaction also was associated with poor graft outcome. The patients interviewed for this study represented a subset of a larger cohort and it is relevant to consider to what extent they were representative of the group as a whole. We were unable to separate the populations on the basis of sex, age at graft, year of graft, or indication for graft, but there is evidence that the patients who were not interviewed may have had a poorer outcome overall. Certainly, more of their grafts had failed. These patients may perhaps have increased the numbers of dissatisfied graft recipients further. However, we consider that this does not negate the major findings of this study: that satisfaction is related to better acuity in the graft than in the contralateral eye, to graft clarity, and to a perception by the patient that his or her life has been improved by the procedure. For a corneal graft procedure to be of benefit to the majority of patients undergoing corneal transplantation, a number of conditions must be met. The grafted eye must be capable of visual perception, that is, there must be no serious comorbidities affecting retina, optic nerve, or higher visual processing centers; a good optical performance must be achieved (or be able to be achieved) by the graft, that is, the graft must be clear, with an acceptable (or correctable) degree of spherical correction and of anisometropia; there must be a reasonable likelihood of improvement in visual function as a result of the graft, that is, the Snellen acuity should improve postoperatively; finally, the patient should be capable of deriving some benefit from the improved visual function. Precisely how this last condition can be quantified remains uncertain; in our
study, satisfied patients reported an improvement in their lifestyle after transplantation. The outcome of corneal transplantation may need to be considered in light of patients' perceptions of success which itself may be related to pregraft expectations and attitudes to disability, acceptance of the prescribed correction (especially contact lenses), and the visual function of the contralateral eye as well as the measured visual acuity in the graft. The achievement of patient satisfaction at the completion of surgery and any subsequent rehabilitation depends on the interaction of many interconnected factors. Identification of these factors necessarily requires a somewhat broader approach than the straightforward measurement of visual acuity.
REFERENCES 1. StuftingRD, Sumers KD, Cavanagh HD, et al. Penetrating keratoplasty in children. Ophthalmology 1984; 91: 1222-30. 2. Jager MJ, Hermans LJA, Kok JHC. Visual results after corneal transplantation. Doc Ophthalmol1989; 72:265-71. 3. Kramer SG. Penetrating keratoplasty combined with extracapsular cataract extraction. Am J Ophthalmol1985; 100:129-33. 4. Bishop VLM, Robinson LP, Wechsler AW, Billson FA. Corneal graft survival: a retrospective Australian study. Aust NZ J Ophthalmol1986; 14:133-8. 5. Vblker-Dieben HJ, D'Amaro J, Kok-Van Alphen CC. Hierarchy of prognostic factors for corneal allograft survival. Aust NZ J Ophthalmol 1987; 15:11-8. 6. Epstein RJ, Seedor JA, Dreizen NG, et al. Penetrating keratoplasty for herpes simplex keratitis and keratoconus. Allograft rejection and survival. Ophthalmology 1987; 94:935-44. 7. Sayegh FN, Ehlers N, Farah I. Evaluation of penetrating keratoplasty in keratoconus: nine years follow-up. Acta Ophthalmol 1988; 66: 400-3. 8. Mannis MJ, Zadnik K. Refracting the corneal graft. Surv Ophthalmol 1990; 34:436-40. 9. Perlman EM. An analysis and interpretation of refractive errors after penetrating keratoplasty. Ophthalmology 1981; 88:39-45. 10. Carney LG, Jacobs RJ. Problems remaining after successful keratoplasty for keratoconus. Clin Exp Optom 1989; 72:22-5.
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Abstract: Snellen acuity, reading line, and keratometry were measured in a cohort of 60 patients at 2 or more years after penetrating keratoplasty was performed. Patients were asked to complete a questionnaire to elicit information on their perceptions of visual function and the success of the procedure. Using preferred correction, a Snellen acuity of 6/18 or better was achieved by 65%, and a reading line of N8 or better was achieved by 57% of index grafts. Thirtyeight percent had more than 5 diopters (D) of astigmatism in the graft. Approximately 75% of patients reported satisfaction with their graft (satisfaction being associated with better acuity in the grafted eye than the other eye), graft clarity, and a perceived improvement in lifestyle. Dissatisfaction appeared to be associated with graft failure and problems with contact lens wear. The findings have implications for patient selection for corneal transplantation and for the measurement of outcome. Ophthalmology 1991; 98:651-657
Corneal transplantation is generally considered to be a very successful procedure. However, published studies of long-term visual outcome in cohorts of patients with mixed indications for graft are surprisingly few. 1,2 Outcome may be measured in various ways, with the criteria for success depending primarily on the indication for the surgery. Corneal grafts are most frequently performed for the improvement of visual acuity but may also be performed for the relief of pain or for maintenance of the structural integrity of the globe. The optical outcome after penetrating keratoplasty, as measured by conventional indices such as graft clarity Originally received: November 5, 1990. Revision accepted: January 14, 1991. From the Department of Ophthalmology, Flinders University of South Australia, Adelaide. Supported by Flinders Medical Centre Research Foundation, the Pank Ophthalmic Trust, and the NH & MRC (grant 890858). Reprint requests to K. A. Williams, PhD, Department of Ophthalmology, Flinders Medical Centre, Bedford Park SA 5042, Australia.
and keratometry, does not always parallel the visual out-
come,' and occasionally neither observed optical nor vi-
sual result seems to match the patients' own perceptions of the apparent degree of success of the procedure. It is not always clear whether such disparities reflect unrealistic expectations on the part of the patient, inadequate pregraft counseling, or unrecognized factors affecting visual rehabilitation, whether physiological or social. We are not aware of any systematic study of corneal graft recipients' assessments of the benefits of their surgery, nor of any attempt to correlate objective measures of visual outcome with patients' subjective perceptions of the result. Our approach was to measure Snellen acuity, reading acuity, and astigmatism in both eyes of a substantial cohort of patients at 2 or more years postgraft. All patients had been treated in a single center by the same surgeon and had received consistent follow-up. We reasoned that by 2 years postkeratoplasty, all graft sutures were likely to have been removed, all refractive surgery on the grafted eye completed, any factors affecting visual result that were essentially unconnected with the actual graft would have been dealt with or would have stabilized, and a reasonably 651
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Table 1. Indication for Graft in the Interviewed Population Indication for Graft Keratoconus Failed previous graft HSV keratitis inactive with corneal scar active] HZO (inactive with corneal scar) Aphakic bullous keratopathy Corneal scart Interstitial keratitis§ Lipid keratopathy'' Fuchs' dystrophy
No. Patients
29
Percent
48
9*
15
4
12
3 1 5 4
2 2
1
2 8 7 3 3 2
HSV = herpes simplex virus; HZO = herpes zoster ophthalmicus. * One case with bacterial superinfection. t Two cases with impending perforation; 1 case with bacterial superinfection. t Two cases with old traumatic injury. § One case luetic, 1 case old trachoma. II One case with recurrent ulceration.
stable refraction should have been achieved. A number of objective measures of visual outcome were then determined, and the patients' feelings about the graft, their perceptions of any changes resulting from the graft, their estimation of the overall success of the procedure, and the extent to which their prior expectations had been met were assessed by means of a questionnaire.
MATERIALS AND METHODS PATIENTS
The beginning patient population consisted of 209 consecutive recipients of a penetrating corneal graft who had undergone their keratoplasty procedure at least 24 months before the start of the study. Seventy-seven patients were excluded at the outset because of death in the intervening period, known serious illness (including dementia), residence at a distance of more than 500 km from the study center, or graft failure followed by recent regraft (with less than 24 months subsequent follow-up). Graft failure alone was not an exclusion criterion. The remaining 132patients were invited to interview. Of these, 41 patients refused to participate or failed to reply, 31 expressed willingness to participate but were unable to travel to the clinic during the time set aside for the study, and 60 attended for interview, were assessed, and completed a questionnaire. These 60 formed the interviewed study population. Informed consent for the study was requested and obtained from all patients. STRUCTURED INTERVIEW
Assessment of visual outcome and patient perception of outcome were determined in a structured interview. All interviews were conducted by the same individual, 652
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who was totally unconnected with the eye clinic and was not involved in any aspect of the care of eye patients. In each case, the interviewer stressed past and continuing independence from the eye care team and assured the patient that the responses to the questionnaire would be kept confidential. Objective measures of visual outcome were then taken and the patient was guided through the questionnaire by the interviewer. An interpreter was called in when necessary. For the one patient younger than 10 years of age, the questionnaire was answered by the child's mother. QUESTIONNAIRE
The questionnaire, validated during a pilot project, contained 24 questions with predominantly either/or responses, together with provision for patients' comments. Questions related to satisfaction with prescribed correction and counseling, and perceptions of visual outcome in terms of function (ability to work and perform tasks of daily living), cosmesis, relief of pain, and prior expectations. MEASUREMENTS OF VISUAL ACUITY AND FUNCTION
Snellen acuity, reading line, and keratometry readings were measured for each eye independently, using the preferred correction. The preferred correction was defined as the method of correction (spectacles or contact lens or neither) currently in daily use by the patient, irrespective of whether that correction had been prescribed by the consultant ophthalmologist. Uncorrected Snellen acuity and acuity with pinhole also were measured. All measurements were made under the same conditions of ambient illumination. Where a decision was made as to the better eye and no difference was measurable between the two eyes, the grafted eye was counted as the better eye. STATISTICAL ANALYSIS
Chi-square contingency table tests with continuity correction were used to test associations with patient satisfaction. For two by two tables in which there were fewer than 5 observations per cell, the Fisher's exact test was employed.
RESULTS INTERVIEWED STUDY POPULATION
For the 60 patients who were interviewed, follow-up ranged from 2.2 to 9.1 years (mean, 4.9 years). All grafts had been performed by the one surgeon between 1980 and 1987. Recipient age at graft varied from 2 to 81 years (mean, 42 years). Indications for graft in the index eye are presented in Table 1. In this series, 50 (83%) patients were grafted in an attempt to improve visual acuity, 4 (7%) patients were grafted to maintain the integrity of the eye, and 6 (l 0%) received a graft primarily for the relief
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OUTCOME OF CORNEAL TRANSPLANTATION
K READINGS IN GRAFT
of pain but also in the expectation of improved visual outcome. Twenty-three percent had bilateral corneal grafts, and, in these patients, the index graft was chosen as the graft with the longer period of follow-up. Fiftythree percent of recipients were working or studying and 47% were home-based or retired. COMPARISON BETWEEN INTERVIEWED AND NONINTERVIEWED POPULATIONS
The interviewed study population was compared both with the total cohort and with the 132 patients invited to interview, with respect to sex, age at graft, calender year of graft, and indication for graft, and was found not to differ significantly from either (P > 0.05, chi-square test). In particular, keratoconus and failed previous grafts were the commonest indications for graft, while pseudophakic bullous keratopathy was rare (n = 2 overall). Additional confounding influences might include variations in graft clarity and in visual acuity. The interviewed population (n = 60) was accordingly compared with the patients (n = 72) invited for interview but who did not attend. Graft clarity and Snellen acuity in the latter group were determined from the notes, using the data recorded at the last time offollow-up. The lengths oftime from graft to followup and from the time of last follow-up to the date of analysis in this group were quite variable, but whereas 8 of 60 grafts had failed in the interviewed group, 22 of 72 grafts were recorded as having failed in the group that did not attend (P < 0.05, chi-square test). Snellen acuities in the noninterviewed population had not been recorded for 11 % and the remainder were a mixture of uncorrected and best-corrected values; however, 38% of the total had achieved a visual acuity of 6/18 or better in the grafted eye, which is not as good as in the interviewed population (see below). Therefore, we were unable to separate the interviewed group from the invited but not interviewed group on the basis of preoperative factors, but the available evidence suggests that the latter group have, in fact, fared less well since the graft. OBJECTIVE MEASURES OF VISUAL OUTCOME: INTERVIEWED POPULATION
The optical status of the graft was determined by graft clarity and keratometry. Graft clarity. Eight index grafts (13%) had failed (4 cases of irreversible rejection, 2 of which were complicated by glaucoma, 1 case each of corneal decompensation in an aphake, epithelial downgrowth, traumatic rupture, and recurrent herpetic infection). Keratometry. Keratometry readings were used to determine the degree of residual astigmatism (Fig 1).Thirtyeight percent of patients had greater than 5 diopters (D) of astigmatism or irregular mires in the grafted eye and 9 patients (15%), all with keratoconus, had greater than 5 D of astigmatism in both eyes. Refractive surgery postgraft had been performed on 8 patients (5 relaxing incisions, 1 relaxing incisions plus wedge resection, and 2 adjustment of graft sutures).
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Visual function was assessedby means of Snellen acuity and reading line measurements and by prescribed correction. Visual acuity. Snellen acuity at 2 or more years after graft in the grafted eye, the other eye, and the better of the two eyes, measured with the preferred correction in each case, is shown in Figure 2. Using the preferred correction, a visual acuity of 6/18 or better was achieved by 65% of recipients in the grafted eye, by 78% in the other eye, and by 92% in the better of the two eyes. Reading ability. Reading line for the graft, the other eye, and for the better eye, measured with preferred correction in each case, is shown in Figure 3. A reading line of N8 or better was achieved by 57% of patients in the grafted eye, by 57% in the other eye, and by 67% in the better of the two eyes. Prescribed correction. Fifty-two percent of patients had been prescribed spectacles, 17% had been prescribed contact lenses, 20% had both spectacles and contact lenses, and 11 % required no correction. VISUAL BEHAVIOR AND PATIENT SATISFACTION
Visual behavior and patient satisfaction were measured with the questionnaire. Visual behavior. Patient responses to the questionnaire are summarized in Tables 2 through 6. Approximately 75% of graft recipients reported that they were managing the tasks of daily living quite successfully (Table 2). However, some patients commented that their capacity to function adequately depended on the level of ambient light. A major difficulty appeared to be with reading fine print, but, nevertheless, 73% of patients reported that they 653
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Fig 2. Snellen acuity in the graft. the other eye, and the better eye, measured with preferred correction. CF = cou nt fingers at I mete r, HM = hand motion; LP = light perceptio n; NLP = no light perception.
654
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Table 2. Questionnaire Responses: Activities of Daily Living Question
Yes
Can you manage your hobbies and leisure activities? Can you read whatever you want to read? Do you drive a car? Can you recognize peoples' faces most of the time? Can you move unaided in unfamiliar surroundings? Does your vision restrict you in your daily living:
77% 73% 63% 80% 82% 40%
No
Table 3. Questionnaire Responses: Perceptions of Postoperative Changes
N/A*
23% 27% 20% 17% 20% 18% 60%
* N/A = not applicable (e.g., patient had never learned to drive orhad no access to a car).
could read whatever they wished. Forty percent of patients believed that their overall vision restricted desired activities, especially leisure activities of which they had once been capable. Such activities included flying an airplane, playing golf, contact sports, tennis, lawn bowling, sewing, and gardening. Approximately 66% of recipients believed that their vision had improved as a result of the graft, 33% believed that their ability to work or study had improved, and approximately 50% believed that their lifestyle had improved (Table 3). However, approximately 25% ofpatients believed that their counseling, before graft placement, had been inadequate and 10 to 13% reported that they had not been told of the possibilities of graft failure, of less than perfect vision, or the probable need for glasses or contact lenses postoperatively (Table 4). The clinical staff involved were unequivocal in their certainty that all patients without exception had been carefully and appropriately counseled. We considered that perhaps those patients who had required emergency grafts (ofwhom there were four), might not have been counseled because of lack of time. However, 3 of these 4 patients considered that they had been well counseled. The fourth patient spoke poor English and it was not possible to establish whether effective communication had been established at the time of graft placement. Although the majority of patients believed that their graft had been worthwhile and were of the opinion that they would make the same decision (to have the graft) again, less than half believed that the outcome had matched their pregraft expectations (Table 5). This discrepancy seemed to be related neither to the incidence or severity of postoperative complications (approximately a third of recipients reported more complications than expected, a third reported fewer than expected, and a third reported as many as expected) nor to a perceived lack of counseling, but rather to a natural (if unrealistic) hope that all would be well, as evinced by the comments made at the interview. Eighty-six percent of patients who were prescribed spectacles and 50% of those who were prescribed contact lenses reported that they disliked wearing their prescribed correction. Of the recipients prescribed spectacles or contact lenses, most (89%) did actually use them. However, not all patients who reported that they used their spectacles or contact lenses in daily living (preferred correction) were necessarily happy with them.
Question
Yes
No
No change or uncertain
Since your graft and as a result of your grafl: Has your vision improved? Has your ability to work improved? Has your social life improved? Has your appearance improved? Has your lifestyle improved?
67% 38% 22% 8% 52%
7% 8% 7%
32% 55% 70% 85% 47%
Table 4. Questionnaire Responses: Pregraft Counseling Question
Yes
No*
Were you appropriately counseled before graft? Were you told your graft might fail? Were you told your vision might not be perfect? Were you told you might need glasses or contact lenses?
75% 82%
23% 10%
83%
13%
80%
13%
* Replies do not add up to 100% across rows because some patients were uncertain or were unable to remember. Table 5. Questionnaire Responses: Patient Expectation and Satisfaction Question
Yes
No
Uncertain or N/A
Are you happy with your graft outcome? Does the outcome match your expectations? Would you make the same decision (to have a graft) again? Was having the graft worthwhile? Have you had more complications than you expected, since graft? Overall, are you very happy with your graft?
80% 47%
20% 45%
8%
87% 93%
13% 3%
3%
28% 70%
70%* 10%
20%
N/A = not applicable. * 30% had fewer than expected. Table 6. Patient Satisfaction and Snellen Acuity in the Belter Eye Patient Satisfaction
Snellen Acuity Belter in: Other Eye Graft*
Total
Patient satisfied Patient dissatisfied
27 4
18 11
45 15
Total
31
29
60
* Where best-corrected acuities in each eye were the same, the graft was counted as the better eye. P = 0.037 (Fisher's exact probability test).
Patient satisfaction. Overall patient satisfaction was assessed on the basis of the answers to what was essentially the same question, repeated twice, once near the beginning of the questionnaire and once close to the end. Satisfied patients were defined as those giving positive responses 655
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to these questions, dissatisfied patients as those giving negative responses, and patients with mixed feelings as those giving discordant responses. Patients with mixed or ambivalent feelings were included with the dissatisfied patients. Ofthe sixgrafts performed for reliefof pain, fivepatients (all with surviving grafts) were pleased with their graft outcome; one, whose graft had failed, was dissatisfied. Of the four grafts performed for structural repair, three patients (two with surviving grafts, one with a failed graft) were satisfied with the outcome, whereas one patient (with a failed graft) was dissatisfied. Of the 50 grafts performed for improvement in visual function , 37 patients professed to be satisfied (35 with clear grafts, 2 with failed grafts) and 13 were unhappy (10 with clear grafts, 3 with failed grafts). A significant association was found between graft outcome (i.e., graft clarity) and recipient satisfaction (P < 0.02, Fisher's exact test). No significant association (corrected P > 0.05, chisquare test) was found between patient satisfaction and a specific level of Snellen acuity using preferred correction (levels tested: better or equal to 6/6, 6/12 , 6/18, 6/60) . However, a significant association was found between patient satisfaction and better Snellen acuity (with preferred correction) in the grafted eye than in the other eye (Table 6; P < 0.05, Fisher's exact test). No association was noted between satisfaction and the presence or absence of more than 5 D of astigmatism or irregular mires in the grafted eye or patient age at graft. Answers to all the questions concerning activities of daily living, perceptions of postoperative changes, pregraft counseling, expectations, and satisfaction with the method of correction were tested individually against patient satisfaction. No correlation was found between answers to most questions and satisfaction. Satisfied patients were more likely to report an improved ability to work or study, a perceived improvement in lifestyle, and that their preoperative expectations had been met, but, of these, only the association with reported improved lifestyle reached significance (P < 0.002, Fisher's exact test). Of the 15 patients expressing a degree ofdissatisfaction with their corneal graft, 8 reported substantial unhappiness, as assessed by negative responses to the questions relating to satisfaction with the graft and provision of additional , unsolicited comments to the effect that they were very unhappy. No one factor stood out to mark these 8 patients. Three patients had failed grafts. In the other five patients, Snellen acuities in the graft (with preferred correction) were 6/6 , 6/9, 6/9 , 6/12, and counting fingers at 1 meter, and astigmatism 3.6,4.6, 11.4, 12, and over 8 D, respectively. These five patients all reported difficulty with contact lens wear, and, indeed , this factor appeared to be a major source of unhappiness with the grafts. PATIENT COMMENTS
The opportunity for patients to provide additional, unsolicited information was provided at the end of each structured interview. Among the most commonly proffered comments were that glare was a continuing problem and that driving at night was difficult; that the constantly 656
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changing refraction in the first year or so after graft was unexpected, annoying, and expensi ve; and that before graft placement, it would have been a help to have been able to talk to someone else who had already undergone corneal transplantation. Some patients commented that they had been unable to absorb all the information given to them in the clinic, but that the y were too embarrassed or diffident to seek further clarification.
DISCUSSION An important determinant of corneal graft outcome is the time after graft placement at which measurements are taken. In assessments of the risk factors associated with overall corneal graft survival, life table analyses allow survival probabilities to be plotted as a function of time postgraft. 1,4-6 Measurements of visual outcome, however, are generally made at one or more specific time points, although it is generally accepted that such measurements alter with time. 2 •7 We chose to examine visual outcome and patient satisfaction at 2 or more years postoperatively, at a time when the constantly changing refraction associated with the early postkeratoplasty period " and with the removal of graft sutures? had stabilized. A decision was made at the outset of this study to use patient-preferred correction (sometimes called social correction) in the measurements of Snellen acuity and reading line, to obtain accurate measures of actual visual functioning. Using the preferred correction, a Snellen acuity of 6/ 18 or better was achieved by 65% and a reading line of N8 or better was achieved by 57% of index grafts. The question of stereopsis was not specifically addressed, although this would be a useful measure in further studies. Visual outcome is a function of the person, rather than the grafted eye: considering the better of the two eyes, 92% of the cohort achieved a Snellen acuity of 6/18 or better and 67% were able to read N8 or better. Thus, the group as a whole did not appear to be particularly visually disabled. However, it was noteworthy that 20 to 30% of patients expressed some degree of disappointment with the outcome of their grafts, with 13% being extremely dissatisfied, and that 40% considered that their overall vision (assessed as a function of both eyes) restricted them in daily living. Of some interest was the almost universally expressed comment that glare remained a problem in the grafted eye. Some loss of visual function has previously been reported in the presence of glare. 10 Unexpectedly, satisfaction was not associated with the achievement of a specific, high level of measured acuity in the grafted eye, but rather with achievement of a better Snellen acuity (at any level) in the grafted eye than in the other eye. Some patients with quite poor Snellen acuity in their grafted eye, nonetheless reported that they were very pleased with the outcome. This finding may have some ramifications for patient selection for corneal transplantation, given the general shortfall in corneal donor material. Where material is limited, it may be appropriate to consider the status of the other eye and to refrain from surgery if it is believed that a better visual result in the
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OUTCOME OF CORNEAL TRANSPLANTATION
eye under consideration for graft cannot readily be achieved. However, achievement of navigable vision in the grafted eye may be of benefit to the patient with even poorer visual function in the other eye. A further consideration relates to the patient's willingness to wear contact lenses postoperatively, given that problems with lens wear appeared to be associated with dissatisfaction, irrespective of the visual result obtained with the graft. Not surprisingly, dissatisfaction also was associated with poor graft outcome. The patients interviewed for this study represented a subset of a larger cohort and it is relevant to consider to what extent they were representative of the group as a whole. We were unable to separate the populations on the basis of sex, age at graft, year of graft, or indication for graft, but there is evidence that the patients who were not interviewed may have had a poorer outcome overall. Certainly, more of their grafts had failed. These patients may perhaps have increased the numbers of dissatisfied graft recipients further. However, we consider that this does not negate the major findings of this study: that satisfaction is related to better acuity in the graft than in the contralateral eye, to graft clarity, and to a perception by the patient that his or her life has been improved by the procedure. For a corneal graft procedure to be of benefit to the majority of patients undergoing corneal transplantation, a number of conditions must be met. The grafted eye must be capable of visual perception, that is, there must be no serious comorbidities affecting retina, optic nerve, or higher visual processing centers; a good optical performance must be achieved (or be able to be achieved) by the graft, that is, the graft must be clear, with an acceptable (or correctable) degree of spherical correction and of anisometropia; there must be a reasonable likelihood of improvement in visual function as a result of the graft, that is, the Snellen acuity should improve postoperatively; finally, the patient should be capable of deriving some benefit from the improved visual function. Precisely how this last condition can be quantified remains uncertain; in our
study, satisfied patients reported an improvement in their lifestyle after transplantation. The outcome of corneal transplantation may need to be considered in light of patients' perceptions of success which itself may be related to pregraft expectations and attitudes to disability, acceptance of the prescribed correction (especially contact lenses), and the visual function of the contralateral eye as well as the measured visual acuity in the graft. The achievement of patient satisfaction at the completion of surgery and any subsequent rehabilitation depends on the interaction of many interconnected factors. Identification of these factors necessarily requires a somewhat broader approach than the straightforward measurement of visual acuity.
REFERENCES 1. StuftingRD, Sumers KD, Cavanagh HD, et al. Penetrating keratoplasty in children. Ophthalmology 1984; 91: 1222-30. 2. Jager MJ, Hermans LJA, Kok JHC. Visual results after corneal transplantation. Doc Ophthalmol1989; 72:265-71. 3. Kramer SG. Penetrating keratoplasty combined with extracapsular cataract extraction. Am J Ophthalmol1985; 100:129-33. 4. Bishop VLM, Robinson LP, Wechsler AW, Billson FA. Corneal graft survival: a retrospective Australian study. Aust NZ J Ophthalmol1986; 14:133-8. 5. Vblker-Dieben HJ, D'Amaro J, Kok-Van Alphen CC. Hierarchy of prognostic factors for corneal allograft survival. Aust NZ J Ophthalmol 1987; 15:11-8. 6. Epstein RJ, Seedor JA, Dreizen NG, et al. Penetrating keratoplasty for herpes simplex keratitis and keratoconus. Allograft rejection and survival. Ophthalmology 1987; 94:935-44. 7. Sayegh FN, Ehlers N, Farah I. Evaluation of penetrating keratoplasty in keratoconus: nine years follow-up. Acta Ophthalmol 1988; 66: 400-3. 8. Mannis MJ, Zadnik K. Refracting the corneal graft. Surv Ophthalmol 1990; 34:436-40. 9. Perlman EM. An analysis and interpretation of refractive errors after penetrating keratoplasty. Ophthalmology 1981; 88:39-45. 10. Carney LG, Jacobs RJ. Problems remaining after successful keratoplasty for keratoconus. Clin Exp Optom 1989; 72:22-5.
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