- Email: [email protected]
Improvement in best corrected visual acuity in amblyopic adult eyes after laser in situ keratomileusis
Improvement in best corrected visual acuity in amblyopic adult eyes after laser in situ keratomileusis Keiko Sakatani, MD, Nada S. Jabbur, MD, Terrence P. O’Brien, MD Purpose: To evaluate improvement in best spectacle-corrected visual acuity (BSCVA) after laser in situ keratomileusis (LASIK) in adult patients with amblyopia. Setting: Refractive Eye Surgery Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. Methods: The charts of consecutive patients with a diagnosis of amblyopia at the time of refractive evaluation who had LASIK were reviewed retrospectively. The preoperative and postoperative uncorrected visual acuity (UCVA) and BSCVA were analyzed. Results: Twenty-one eyes of 19 patients were identified as having amblyopia and LASIK surgery. Eight patients (42.1%) were diagnosed with amblyopia only, 6 patients (31.6%) had anisometropic amblyopia, 4 patients (21.1%) had strabismic amblyopia, and 1 patient (5.2%) had anisometropic and strabismic amblyopia. Eleven eyes (52.4%) had myopic astigmatism, 7 eyes (33.3%) were hyperopic, and 3 eyes (14.3%) had mixed astigmatism. Seven eyes (33.3 %) experienced more than a 1-line improvement in postoperative UCVA compared with the preoperative BSCVA. Nine eyes (42.8%) experienced more than a 1-line improvement in postoperative BSCVA compared with the preoperative BSCVA. The BSCVA was unchanged in 11 eyes (52.4%) and was worse by 2 lines in 1 eye (4.8%). Conclusion: After LASIK, the postoperative BSCVA was better than preoperatively in 42.8% of eyes with a history of amblyopia and the postoperative UCVA was better than the preoperative BSCVA in 33.3%. J Cataract Refract Surg 2004; 30:2517–2521 ª 2004 ASCRS and ESCRS
V
isual experience in infancy and early childhood is critical to the development of normal visual pathways.1,2 Interruption of visual experience can result in amblyopia. Strategies to prevent amblyopia in children
Accepted for publication April 23, 2004. From the Refractive Eye Surgery Service, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. Presented at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA, May 2003. None of the authors has a financial interest in any product mentioned. Reprint requests to Terrence P. O’Brien, MD, Director, Refractive Eye Surgery, Wilmer Eye Institute at Greenspring Station, Johns Hopkins University School of Medicine, 10753 Falls Road, Suite 455, Lutherville, Maryland 21093, USA. E-mail: [email protected]. ª 2004 ASCRS and ESCRS Published by Elsevier Inc.
apply aggressive intervention to improve and recover as much best spectacle-corrected visual acuity (BSCVA) as possible during the critical period in the development of vision.3–5 Unilateral high myopia is reported to be the type of anisometropic amblyopia that is most refractory to treatment.6 In pediatric patients, excimer laser photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) has been suggested as a potential treatment for highly asymmetric ametropias when contact lens (CL) wear is not safe or feasible to prevent the development of amblyopia.7–12 In adults, there have been limited efforts to date to improve amblyopia even slightly because of the suspected permanency of the deficit.13–17 Based on observations of individual clinical outcomes and subjective postoperative reports, we 0886-3350/04/$-see front matter doi:10.1016/j.jcrs.2004.06.026
IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
suspected there was a minimal improvement in the visual performance of adult amblyopic eyes in patients who consulted at our refractive surgery center and had primary laser vision correction of their refractive error including myopia, hyperopia, and mixed astigmatism.
Patients and Methods The charts of patients with a diagnosis of amblyopia at the time of the initial refractive evaluation who had LASIK at the Refractive Eye Surgery Center of the Wilmer Eye Institute were reviewed. All patients gave written permission for their ocular data to be included anonymously and reviewed through the database. The patients had LASIK to improve their uncorrected visual acuity (UCVA) at distance. Patients were informed preoperatively that the aspects of their vision related to amblyopia would probably not improve with LASIK. The following categories were reviewed and recorded for each patient: age and sex, type of amblyopia (amblyopia only, amblyopia with anisometropia, amblyopia with strabismus), previous treatment for amblyopia (medical and surgical), history of CL wear, initial refractive error, and preoperative and postoperative UCVA and BSCVA. Analysis of the refractive data18 was performed and included comparison of preoperative UCVA and BSCVA with postoperative UCVA and BSCVA to detect improvements in amblyopic eyes following LASIK. All visual acuities were measured using letters on the B-VAT PC Visual Acuity System (Medtronic Solan) and recorded in a standardized fashion in which each letter read on a complete line was noted accordingly. Changes in preoperative BSCVA, postoperative UCVA, and postoperative BSCVA were recorded in logMAR units; a change of 0.1 unit corresponded to a line of vision. In all eyes, LASIK was performed using the Hansatome (Bausch & Lomb) or Amadeus (Advanced Medical Optics) microkeratome and the Visx Star S3 or S4 excimer laser. Two eyes had a retreatment after primary LASIK. Statistical analysis included the use of the Student t test to determine the validity of the between-group comparisons.
Results Nineteen consecutive patients (21 eyes) with a history of amblyopia who had LASIK were seen by 1 of 2 surgeons (N.S.J., T.P.O’B.) between August 2000 and February 2003. Age and Sex The mean age of the 7 women and 12 men was 41.1 years (range 22 to 62 years). 2518
Amblyopia Seventeen patients had unilateral amblyopia and 2 patients, bilateral amblyopia. Six patients (31.6%) had anisometropic amblyopia, 4 patients (21.1%) had strabismic amblyopia, and 1 patient (5.2%) had anisometropic and strabismic amblyopia. Previous Treatment for Amblyopia (Medical and Surgical) Eleven eyes of 9 patients were treated for amblyopia using 1 or more of the following therapies: patching (7 eyes), muscle exercises (1 eye), and strabismus surgery (5 eyes). No patients had pharmacologic penalization therapy; this modality was not widely used when these adult patients were younger. History of Contact Lens Wear Ten eyes had a history of CL wear (7 eyes used a soft CL and 2 eyes, a rigid gas-permeable CL; 1 eye used both types). Preoperative Refractive Error Eleven amblyopic eyes had myopia with astigmatism. The mean myopic sphere was ÿ5.73 diopters (D) (range ÿ3.00 to ÿ6.75 D), the mean cylinder was C1.39 D (range C0.50 to C3.75 D), and the mean manifest refraction spherical equivalent (MRSE) was ÿ5.04 D (range ÿ2.50 to ÿ6.37 D). Seven amblyopic eyes had hyperopia with astigmatism. The mean hyperopic sphere was C2.46 D (range C0.50 to C4.00 D), the mean cylinder was C1.29 D (range 0 to C2.75 D), and the mean MRSE was C3.11 D (range C1.37 to C4.25 D). Three amblyopic eyes had mixed astigmatism. The mean MRSE was ÿ0.46 D (range ÿ1.00 to C0.37 D) (Table 1). Preoperative UCVA and BSCVA Preoperative visual acuities were obtained at the initial refractive evaluation and are summarized in Table 1. The mean preoperative BSCVA was 20/35 (C0.24 in logMAR) (range 20/300 to 20/20ÿ). Postoperative UCVA and BSCVA Postoperative visual acuities were obtained at the patients’ last clinical visit (mean follow-up 226 days, range 36 to 731 days) and are summarized in Table 1.
J CATARACT REFRACT SURG —VOL 30, DECEMBER 2004
IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
Table 1.
Preoperative and postoperative fingings in amblyopic patients. Preoperative
Postop UVCA (Snellen)
UCVA
MR
BSCVA (Snellen)
1
20/>400
ÿ6.25 C1.50 ! 175
20/300
C1.18
237
20/200
2
20/>400
ÿ5.75 C0.50 ! 25
20/40C
C0.28
237
20/30ÿ
3
20/>400
ÿ4.50 C1.25 ! 160
20/30ÿ
C0.20
110
20/20
ÿ
BSCVA (logMAR)
Follow-up (Days)
Patients
4
20/>400
ÿ6.25 C0.75 ! 40
20/40
C0.32
408
20/40ÿ3
5
20/>400
ÿ6.50 C3.75 ! 80
20/20C
ÿ0.02
600
20/20ÿ2
ÿ
6
20/>400
ÿ5.50 C1.00 ! 15
20/25
C0.12
153
20/25C
7
20/400
ÿ3.00 C1.00 ! 65
20/25
C0.10
514
20/40
8a
20/>400
ÿ6.50 C0.75 ! 95
20/25
C0.10
139
20/20ÿ
8b
20/>400
ÿ6.75 C0.75 ! 80
20/25
C0.10
139
20/25C2
ÿ
9
20/>400
ÿ6.00 C1.25 ! 80
20/40
C0.32
62
20/50C
10
20/>400
ÿ6.00 C2.75 ! 105
20/50C
C0.38
43
20/30ÿ2
11
20/300
C3.25 C1.50 ! 170
20/60
C0.48
731
20/60
12
20/100
C1.00 C2.75 ! 101
20/30C
C0.16
36
20/40C
13
20/>400
C4.00 C0.50 ! 95
20/25ÿ
C0.12
277
20/30
ÿ
14
20/80
C0.50 C1.75 ! 175
20/20
C0.02
370
20/40C
15
20/200
C3.25 C0.50 ! 05
20/25
C0.10
106
20/20C2
16
20/100
C2.75 C2.00 ! 155
20/60
C0.48
97
20/60C2
17
20/200
20/30
C0.16
71
20/20C
18a
20/80
ÿ2.75 C3.50 ! 110
20/25
C0.10
190
20/25C2
18b
20/63
ÿ2.50 C3.50 ! 66
20/32C
C0.18
190
20/20
19
20/200
ÿ2.25 C5.25 ! 83
20/25C
C0.08
37
20/30ÿ
C
C2.50 sph
C
a, b Z bilateral cases; BSCVA Z best spectacle-corrected visual acuity; MR Z manifest refraction; UCVA Z uncorrected visual acuity
The mean postoperative UCVA was 20/33 (C0.22 in logMAR) (range 20/200 to 20/20C2) and the mean postoperative BSCVA, 20/29 (C0.16 in logMAR) (range 20/200 to 20/15ÿ3). Seven of 21 eyes (33.3 %) had at least a 1-line improvement in the postoperative UCVA compared with the preoperative BSCVA. This improvement was not statistically significant. Nine of 21 eyes (42.8%) had at least a 1-line improvement in the postoperative BSCVA compared to the preoperative BSCVA. This improvement was statistically significant (P!.01, Student t test). One eye (4.8%) lost 2 lines of BSCVA associated with epithelial ingrowth. A LASIK retreatment procedure was performed in this eye. Preoperative and postoperative BSCVAs were analyzed by stratifying the eyes as follows: Stratification by Type of Amblyopia. The improvement in BSCVA was statistically significant in eyes that had strabismic amblyopia (P!.01) (Table 2).
Stratification by History of Treatment for Amblyopia as a Child. The improvement in BSCVA was statistically significant in the patients who received treatment for amblyopia as children (P Z .001) (Table 3). Stratification by History of CL Wear. The improvement in BSCVA was better in the CL group (P Z .011) (Table 4). Stratification by Initial Refractive Error. The improvement in BSCVA was statistically significant in amblyopic eyes that had myopia (P!.01) but not in amblyopic eyes that had hyperopia or mixed astigmatism (Table 5).
Discussion Refractive surgery with excimer laser photoablative keratectomy has become a common treatment for correction of a range of refractive errors. Recently, many authors have reported the efficacy of excimer
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2519
IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
laser vision correction for anisometropic amblyopia in children.7–12 However, there is a general consensus that the critical period in which best corrected vision can be improved with any amblyopia preventive therapy is up to approximately 8 years of age, after which success in recovery of visual acuity diminishes.3–5 Nevertheless, several reports now describe the successful treatment of amblyopia with improvement in BSCVA in older children and adults.8,13–17 Simmers and Gray15 report a case of a 30-year-old patient with strabismic amblyopia treated with aggressive occlusion Table 2.
Type of amblyopia. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Amblyopia only (n Z 8)
20/32
20/29
.397
With anisometropia (n Z 7)
20/33
20/27
.038
With strabismus (n Z 7)
20/38
20/29
.008
BSCVA Z best spectacle-corrected visual acuity
Table 3.
History of treatment for amblyopia as a child. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Treatment (n Z 11)
20/42
20/33
.001
No treatment (n Z 10)
20/28
20/25
.315
BSCVA Z best spectacle-corrected visual acuity
Table 4.
History of CL wear. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
CL (n Z 10)
20/40
20/34
.011
No CL (n Z 11)
20/30
20/26
.142
BSCVA Z best spectacle-corrected visual acuity; CL Z contact lens
Table 5.
Initial refractive error. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Myopia (n Z 11)
20/38
20/31
.009
Hyperopia (n Z 7)
20/33
20/30
.462
Mixed astigmatism (n Z 3)
20/26
20/21
.208
BSCVA Z best spectacle-corrected visual acuity
2520
therapy and suggest that many aspects of an amblyope’s visual function could improve beyond the critical periods for development of normal vision. In our adult patients with refractive errors and a history of amblyopia, the goal was to treat the refractive errors using excimer laser vision correction. The patients understood preoperatively that amblyopia would probably not be reversed or improved with the refractive procedures beyond the preoperative BSCVA. In the postoperative course, we suspected an improvement in BSCVA based on measured visual acuity and subjective patient satisfaction; ie, unsolicited reports of significant improvement in the visual function of the treated amblyopic eye. This was supported by a retrospective analysis documenting that 57% of the patients had a statistically significant improvement in postoperative BSCVA compared with preoperative BSCVA. When we classified the amblyopic eyes by preoperative manifest refraction, those with myopia showed a statistically significant improvement in postoperative BSCVA (P!.01). However, the improvement in visual acuity was not statistically significant in amblyopic eyes that had hyperopia or mixed astigmatism. One mechanism of improvement in visual function could be a change in the magnification of the image obtained in amblyopic eyes with myopia.19 In addition, correction of all refractive errors including astigmatism could be refined at the corneal plane rather than the spectacle plane, similar to correction with a contact lens. When we analyzed the earliest follow-up examination with the best BSCVA achieved per eye, we found that the 12 eyes that demonstrated more than a 1-line improvement in postoperative BSCVA achieved the best vision by 3 months; 7 eyes (58.3%) achieved it by 1 month, 2 eyes (16.7%) by 2 months, and 3 eyes (25.0%) by 3 months. The 3 eyes in which the best vision was attained at 3 months were associated with a preoperative refractive error of mixed astigmatism (2 eyes) and hyperopia (1 eye). It is not uncommon to clinically observe a slower recovery of vision in patients treated for hyperopia and mixed astigmatism, perhaps owing to additional wound-healing recovery time after the more complex patterns of corrective ablations. Unfortunately, we did not obtain wavefront analysis including ocular aberration maps for all patients in the study to determine whether a change in higher-
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IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
order aberrations after LASIK was a contributing factor to the improvement in BSCVA in most treated eyes. Despite the small number of patients in this retrospective review, it appears that adult amblyopic patients—especially those who received amblyopia treatment as children—may benefit from laser vision correction of their residual refractive error by experiencing a small improvement in best corrected acuity (P Z .001). This could be related to a better overall preoperative potential BSCVA. While our findings are encouraging, further investigation is required for better understanding of the underlying mechanism for the observed improvement in BSCVA in adult amblyopic patients having LASIK.
Conclusion In our limited retrospective series, a statistically significant improvement in BSCVA was observed among amblyopic eyes in adults after LASIK, especially in patients who had a history of amblyopia treatment including patching, muscle exercises, and/or strabismus surgery. The precise mechanisms accounting for the observed improvement in BSCVA after LASIK as well as the adult patients with amblyopia who are most likely to benefit from laser vision correction are incompletely understood and warrant further investigation.
References 1. Daw NW. Mechanisms of plasticity in the visual cortex; the Friedenwald Lecture. Invest Ophthalmol Vis Sci 1994; 35:4168–4179; corrections 1995; 36:520 2. Wiesel TN. Postnatal development of the visual cortex and the influence of environment. Nature 1982; 299: 583–591 3. Epelbaum M, Milleret C, Buisseret P, Dufier JL. The sensitive period for strabismic amblyopia in humans. Ophthalmology 1993; 100:323–327
4. Hardman Lea SJ, Loades J, Rubinstein MP. The sensitive period for anisometropic amblyopia. Eye 1989; 3:783– 790 5. Harwerth RS, Smith EL III, Duncan GC, et al. Multiple sensitive periods in the development of the primate visual system. Science 1986; 232:235–238 6. Kutschke PJ, Scott WE, Keech RV. Anisometropic amblyopia. Ophthalmology 1991; 98:258–263 7. Nucci P, Drack AV. Refractive surgery for unilateral high myopia in children. J AAPOS 2001; 5:348–351 8. Nassaralla BRA, Nassaralla JJ Jr. Laser in situ keratomileusis in children 8 to 15 years old. J Refract Surg 2001; 17:519–524 9. Rashad KM. Laser in situ keratomileusis for myopic anisometropia in children. J Refract Surg 1999; 15:429– 435 10. Alio´ JL, Artola A, Claramonte P, et al. Photorefractive keratectomy for pediatric myopic anisometropia. J Cataract Refract Surg 1998; 24:327–330 11. Nano HD Jr, Muzzin S, Irigaray LF. Excimer laser photorefractive keratectomy in pediatric patients. J Cataract Refract Surg 1997; 23:736–739 12. Singh D. Photorefractive keratectomy in pediatric patients. J Cataract Refract Surg 1995; 21:630–632 13. Moseley M, Fielder A. Improvement in amblyopic eye function and contralateral eye disease: evidence of residual plasticity. Lancet 2001; 357:902–904 14. El Mallah MK, Chakravarthy U, Hart PM. Amblyopia: is visual loss permanent? Br J Ophthalmol 2000; 84: 952–956 15. Simmers AJ, Gray LS. Improvement of visual function in an adult amblyope. Optom Vis Sci 1999; 76:82–87 16. Wick B, Wingard M, Cotter S, Scheiman M. Anisometropic amblyopia: is the patient ever too old to treat? Optom Vis Sci 1992; 69:866–878 17. Selenow A, Ciuffreda KJ. Vision function recovery during orthoptic therapy in an adult esotropic amblyope. J Am Optom Assoc 1986; 57:132–140 18. Holladay JT. Proper method for calculating average visual acuity. J Refract Surg 1997; 13:388–391 19. Applegate RA, Howland HC. Magnification and visual acuity in refractive surgery. Arch Ophthalmol 1993; 111:1335–1342
J CATARACT REFRACT SURG —VOL 30, DECEMBER 2004
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V
isual experience in infancy and early childhood is critical to the development of normal visual pathways.1,2 Interruption of visual experience can result in amblyopia. Strategies to prevent amblyopia in children
Accepted for publication April 23, 2004. From the Refractive Eye Surgery Service, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. Presented at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, Florida, USA, May 2003. None of the authors has a financial interest in any product mentioned. Reprint requests to Terrence P. O’Brien, MD, Director, Refractive Eye Surgery, Wilmer Eye Institute at Greenspring Station, Johns Hopkins University School of Medicine, 10753 Falls Road, Suite 455, Lutherville, Maryland 21093, USA. E-mail: [email protected]. ª 2004 ASCRS and ESCRS Published by Elsevier Inc.
apply aggressive intervention to improve and recover as much best spectacle-corrected visual acuity (BSCVA) as possible during the critical period in the development of vision.3–5 Unilateral high myopia is reported to be the type of anisometropic amblyopia that is most refractory to treatment.6 In pediatric patients, excimer laser photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) has been suggested as a potential treatment for highly asymmetric ametropias when contact lens (CL) wear is not safe or feasible to prevent the development of amblyopia.7–12 In adults, there have been limited efforts to date to improve amblyopia even slightly because of the suspected permanency of the deficit.13–17 Based on observations of individual clinical outcomes and subjective postoperative reports, we 0886-3350/04/$-see front matter doi:10.1016/j.jcrs.2004.06.026
IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
suspected there was a minimal improvement in the visual performance of adult amblyopic eyes in patients who consulted at our refractive surgery center and had primary laser vision correction of their refractive error including myopia, hyperopia, and mixed astigmatism.
Patients and Methods The charts of patients with a diagnosis of amblyopia at the time of the initial refractive evaluation who had LASIK at the Refractive Eye Surgery Center of the Wilmer Eye Institute were reviewed. All patients gave written permission for their ocular data to be included anonymously and reviewed through the database. The patients had LASIK to improve their uncorrected visual acuity (UCVA) at distance. Patients were informed preoperatively that the aspects of their vision related to amblyopia would probably not improve with LASIK. The following categories were reviewed and recorded for each patient: age and sex, type of amblyopia (amblyopia only, amblyopia with anisometropia, amblyopia with strabismus), previous treatment for amblyopia (medical and surgical), history of CL wear, initial refractive error, and preoperative and postoperative UCVA and BSCVA. Analysis of the refractive data18 was performed and included comparison of preoperative UCVA and BSCVA with postoperative UCVA and BSCVA to detect improvements in amblyopic eyes following LASIK. All visual acuities were measured using letters on the B-VAT PC Visual Acuity System (Medtronic Solan) and recorded in a standardized fashion in which each letter read on a complete line was noted accordingly. Changes in preoperative BSCVA, postoperative UCVA, and postoperative BSCVA were recorded in logMAR units; a change of 0.1 unit corresponded to a line of vision. In all eyes, LASIK was performed using the Hansatome (Bausch & Lomb) or Amadeus (Advanced Medical Optics) microkeratome and the Visx Star S3 or S4 excimer laser. Two eyes had a retreatment after primary LASIK. Statistical analysis included the use of the Student t test to determine the validity of the between-group comparisons.
Results Nineteen consecutive patients (21 eyes) with a history of amblyopia who had LASIK were seen by 1 of 2 surgeons (N.S.J., T.P.O’B.) between August 2000 and February 2003. Age and Sex The mean age of the 7 women and 12 men was 41.1 years (range 22 to 62 years). 2518
Amblyopia Seventeen patients had unilateral amblyopia and 2 patients, bilateral amblyopia. Six patients (31.6%) had anisometropic amblyopia, 4 patients (21.1%) had strabismic amblyopia, and 1 patient (5.2%) had anisometropic and strabismic amblyopia. Previous Treatment for Amblyopia (Medical and Surgical) Eleven eyes of 9 patients were treated for amblyopia using 1 or more of the following therapies: patching (7 eyes), muscle exercises (1 eye), and strabismus surgery (5 eyes). No patients had pharmacologic penalization therapy; this modality was not widely used when these adult patients were younger. History of Contact Lens Wear Ten eyes had a history of CL wear (7 eyes used a soft CL and 2 eyes, a rigid gas-permeable CL; 1 eye used both types). Preoperative Refractive Error Eleven amblyopic eyes had myopia with astigmatism. The mean myopic sphere was ÿ5.73 diopters (D) (range ÿ3.00 to ÿ6.75 D), the mean cylinder was C1.39 D (range C0.50 to C3.75 D), and the mean manifest refraction spherical equivalent (MRSE) was ÿ5.04 D (range ÿ2.50 to ÿ6.37 D). Seven amblyopic eyes had hyperopia with astigmatism. The mean hyperopic sphere was C2.46 D (range C0.50 to C4.00 D), the mean cylinder was C1.29 D (range 0 to C2.75 D), and the mean MRSE was C3.11 D (range C1.37 to C4.25 D). Three amblyopic eyes had mixed astigmatism. The mean MRSE was ÿ0.46 D (range ÿ1.00 to C0.37 D) (Table 1). Preoperative UCVA and BSCVA Preoperative visual acuities were obtained at the initial refractive evaluation and are summarized in Table 1. The mean preoperative BSCVA was 20/35 (C0.24 in logMAR) (range 20/300 to 20/20ÿ). Postoperative UCVA and BSCVA Postoperative visual acuities were obtained at the patients’ last clinical visit (mean follow-up 226 days, range 36 to 731 days) and are summarized in Table 1.
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IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
Table 1.
Preoperative and postoperative fingings in amblyopic patients. Preoperative
Postop UVCA (Snellen)
UCVA
MR
BSCVA (Snellen)
1
20/>400
ÿ6.25 C1.50 ! 175
20/300
C1.18
237
20/200
2
20/>400
ÿ5.75 C0.50 ! 25
20/40C
C0.28
237
20/30ÿ
3
20/>400
ÿ4.50 C1.25 ! 160
20/30ÿ
C0.20
110
20/20
ÿ
BSCVA (logMAR)
Follow-up (Days)
Patients
4
20/>400
ÿ6.25 C0.75 ! 40
20/40
C0.32
408
20/40ÿ3
5
20/>400
ÿ6.50 C3.75 ! 80
20/20C
ÿ0.02
600
20/20ÿ2
ÿ
6
20/>400
ÿ5.50 C1.00 ! 15
20/25
C0.12
153
20/25C
7
20/400
ÿ3.00 C1.00 ! 65
20/25
C0.10
514
20/40
8a
20/>400
ÿ6.50 C0.75 ! 95
20/25
C0.10
139
20/20ÿ
8b
20/>400
ÿ6.75 C0.75 ! 80
20/25
C0.10
139
20/25C2
ÿ
9
20/>400
ÿ6.00 C1.25 ! 80
20/40
C0.32
62
20/50C
10
20/>400
ÿ6.00 C2.75 ! 105
20/50C
C0.38
43
20/30ÿ2
11
20/300
C3.25 C1.50 ! 170
20/60
C0.48
731
20/60
12
20/100
C1.00 C2.75 ! 101
20/30C
C0.16
36
20/40C
13
20/>400
C4.00 C0.50 ! 95
20/25ÿ
C0.12
277
20/30
ÿ
14
20/80
C0.50 C1.75 ! 175
20/20
C0.02
370
20/40C
15
20/200
C3.25 C0.50 ! 05
20/25
C0.10
106
20/20C2
16
20/100
C2.75 C2.00 ! 155
20/60
C0.48
97
20/60C2
17
20/200
20/30
C0.16
71
20/20C
18a
20/80
ÿ2.75 C3.50 ! 110
20/25
C0.10
190
20/25C2
18b
20/63
ÿ2.50 C3.50 ! 66
20/32C
C0.18
190
20/20
19
20/200
ÿ2.25 C5.25 ! 83
20/25C
C0.08
37
20/30ÿ
C
C2.50 sph
C
a, b Z bilateral cases; BSCVA Z best spectacle-corrected visual acuity; MR Z manifest refraction; UCVA Z uncorrected visual acuity
The mean postoperative UCVA was 20/33 (C0.22 in logMAR) (range 20/200 to 20/20C2) and the mean postoperative BSCVA, 20/29 (C0.16 in logMAR) (range 20/200 to 20/15ÿ3). Seven of 21 eyes (33.3 %) had at least a 1-line improvement in the postoperative UCVA compared with the preoperative BSCVA. This improvement was not statistically significant. Nine of 21 eyes (42.8%) had at least a 1-line improvement in the postoperative BSCVA compared to the preoperative BSCVA. This improvement was statistically significant (P!.01, Student t test). One eye (4.8%) lost 2 lines of BSCVA associated with epithelial ingrowth. A LASIK retreatment procedure was performed in this eye. Preoperative and postoperative BSCVAs were analyzed by stratifying the eyes as follows: Stratification by Type of Amblyopia. The improvement in BSCVA was statistically significant in eyes that had strabismic amblyopia (P!.01) (Table 2).
Stratification by History of Treatment for Amblyopia as a Child. The improvement in BSCVA was statistically significant in the patients who received treatment for amblyopia as children (P Z .001) (Table 3). Stratification by History of CL Wear. The improvement in BSCVA was better in the CL group (P Z .011) (Table 4). Stratification by Initial Refractive Error. The improvement in BSCVA was statistically significant in amblyopic eyes that had myopia (P!.01) but not in amblyopic eyes that had hyperopia or mixed astigmatism (Table 5).
Discussion Refractive surgery with excimer laser photoablative keratectomy has become a common treatment for correction of a range of refractive errors. Recently, many authors have reported the efficacy of excimer
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IMPROVEMENT IN VISION IN AMBLYOPIC ADULTS AFTER LASIK
laser vision correction for anisometropic amblyopia in children.7–12 However, there is a general consensus that the critical period in which best corrected vision can be improved with any amblyopia preventive therapy is up to approximately 8 years of age, after which success in recovery of visual acuity diminishes.3–5 Nevertheless, several reports now describe the successful treatment of amblyopia with improvement in BSCVA in older children and adults.8,13–17 Simmers and Gray15 report a case of a 30-year-old patient with strabismic amblyopia treated with aggressive occlusion Table 2.
Type of amblyopia. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Amblyopia only (n Z 8)
20/32
20/29
.397
With anisometropia (n Z 7)
20/33
20/27
.038
With strabismus (n Z 7)
20/38
20/29
.008
BSCVA Z best spectacle-corrected visual acuity
Table 3.
History of treatment for amblyopia as a child. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Treatment (n Z 11)
20/42
20/33
.001
No treatment (n Z 10)
20/28
20/25
.315
BSCVA Z best spectacle-corrected visual acuity
Table 4.
History of CL wear. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
CL (n Z 10)
20/40
20/34
.011
No CL (n Z 11)
20/30
20/26
.142
BSCVA Z best spectacle-corrected visual acuity; CL Z contact lens
Table 5.
Initial refractive error. Mean BSCVA
Eyes
Preoperative Postoperative
P Value
Myopia (n Z 11)
20/38
20/31
.009
Hyperopia (n Z 7)
20/33
20/30
.462
Mixed astigmatism (n Z 3)
20/26
20/21
.208
BSCVA Z best spectacle-corrected visual acuity
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therapy and suggest that many aspects of an amblyope’s visual function could improve beyond the critical periods for development of normal vision. In our adult patients with refractive errors and a history of amblyopia, the goal was to treat the refractive errors using excimer laser vision correction. The patients understood preoperatively that amblyopia would probably not be reversed or improved with the refractive procedures beyond the preoperative BSCVA. In the postoperative course, we suspected an improvement in BSCVA based on measured visual acuity and subjective patient satisfaction; ie, unsolicited reports of significant improvement in the visual function of the treated amblyopic eye. This was supported by a retrospective analysis documenting that 57% of the patients had a statistically significant improvement in postoperative BSCVA compared with preoperative BSCVA. When we classified the amblyopic eyes by preoperative manifest refraction, those with myopia showed a statistically significant improvement in postoperative BSCVA (P!.01). However, the improvement in visual acuity was not statistically significant in amblyopic eyes that had hyperopia or mixed astigmatism. One mechanism of improvement in visual function could be a change in the magnification of the image obtained in amblyopic eyes with myopia.19 In addition, correction of all refractive errors including astigmatism could be refined at the corneal plane rather than the spectacle plane, similar to correction with a contact lens. When we analyzed the earliest follow-up examination with the best BSCVA achieved per eye, we found that the 12 eyes that demonstrated more than a 1-line improvement in postoperative BSCVA achieved the best vision by 3 months; 7 eyes (58.3%) achieved it by 1 month, 2 eyes (16.7%) by 2 months, and 3 eyes (25.0%) by 3 months. The 3 eyes in which the best vision was attained at 3 months were associated with a preoperative refractive error of mixed astigmatism (2 eyes) and hyperopia (1 eye). It is not uncommon to clinically observe a slower recovery of vision in patients treated for hyperopia and mixed astigmatism, perhaps owing to additional wound-healing recovery time after the more complex patterns of corrective ablations. Unfortunately, we did not obtain wavefront analysis including ocular aberration maps for all patients in the study to determine whether a change in higher-
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order aberrations after LASIK was a contributing factor to the improvement in BSCVA in most treated eyes. Despite the small number of patients in this retrospective review, it appears that adult amblyopic patients—especially those who received amblyopia treatment as children—may benefit from laser vision correction of their residual refractive error by experiencing a small improvement in best corrected acuity (P Z .001). This could be related to a better overall preoperative potential BSCVA. While our findings are encouraging, further investigation is required for better understanding of the underlying mechanism for the observed improvement in BSCVA in adult amblyopic patients having LASIK.
Conclusion In our limited retrospective series, a statistically significant improvement in BSCVA was observed among amblyopic eyes in adults after LASIK, especially in patients who had a history of amblyopia treatment including patching, muscle exercises, and/or strabismus surgery. The precise mechanisms accounting for the observed improvement in BSCVA after LASIK as well as the adult patients with amblyopia who are most likely to benefit from laser vision correction are incompletely understood and warrant further investigation.
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