- Email: [email protected]
Nonvitrectomizing vitreous surgery
Nonvitrectomizing Vitreous Surgery A Strategy to Prevent Postoperative Nuclear Sclerosis Yoshihiro Saito, MD, John M. Lewis, MD, Inwon Park, MD, Yasushi Ikuno, MD, Atsushi Hayashi, MD, Masahito Ohji, MD, Yasuo Tano, MD Objective: The development or progression of postoperative nuclear sclerosis is the most common complication of successful vitrectomy in elderly patients. The authors treated idiopathic epimacular proliferation (EMP) with nonvitrectomizing vitreous surgery in an attempt to prevent postoperative nuclear sclerosis. Design: Prospective, nonrandomized, comparative case series. Participants: The authors surgically removed membranes from the sensory retina in 21 eyes of 21 patients with EMP. Intervention: Neither intravitreal infusion nor vitrectomy of any kind was performed during the procedure. The peeled membrane was left floating in the vitreous cavity in 11 (group 1) eyes and removed in 10 eyes (group 2). Nonoperated fellow eyes served as controls. Main Outcome Measures: Visual acuity, slit-lamp and/or Scheimpflug photography, and refractometry were performed pre- and postoperatively to evaluate changes in the degree of lenticular opacity. Results: There was no difference in the rate of development or progression of nuclear sclerosis or the degree of myopic shift between operated and control eyes during the postoperative follow-up period (mean, 9.7 months). No serious complications were noted. There was no difference in postoperative course between patients in the two operative groups. Conclusions: Although interpretation of the results of this study is limited due to its small size and short follow-up, nonvitrectomizing vitreous surgery seems to decrease the postoperative development or progression of nuclear sclerosis in patients with idiopathic EMP. Ophthalmology 1999;106:1541–1545 Pars plana vitrectomy is an effective treatment for idiopathic epimacular proliferations (EMP). However, visual improvement gained as a result of successful surgery is often lost because of the development or progression of postoperative nuclear sclerosis, which is known to be a frequent complication of vitrectomy for EMP. de Bustros and associates1 reported that 38 (63%) of 60 patients developed nuclear sclerosis an average of 14 months after EMP surgery. Cherfan and associates2 found that 80 (82%) of 97 patients developed nuclear sclerosis in their operated eye 6 months after surgery compared with 24 (23%) of 96 contralateral eyes. They found postoperative nuclear sclerosis to be most significant in patients over 50 years of age. Ogura and associates3 measured lens autofluorescence, a quantifi-
Originally received: June 30, 1998. Revision accepted: May 5, 1999. Manuscript no. 98348. From the Department of Ophthalmology, Osaka University Medical School, Suita, Japan. Presented in part at the Association for Research in Vision and Ophthalmology annual meeting, Fort Lauderdale, Florida, May 1998. Supported by the Grants-in-Aid for Scientific Research (#07557263) from the Ministry of Education, Science and Culture, and Health Science Research Grants, Japan. Address correspondence to Yoshihiro Saito, MD, Department of Ophthalmology, Hyogo Prefectural Nishinomiya Hospital, 13-9 Rokutanji, Nishinomiya 662-0918, Japan. E-mail: [email protected].
able marker for nuclear cataract, and found a significant increase 2 years after EMP vitrectomy. Kawakubo and associates4 used myopic shift as a marker for progression of nuclear sclerosis5,6 and found an average refractive change of 0.9 diopters (D) of myopia 6 months after vitrectomy for EMP. They also reported 11 (22%) of 50 patients had aniseikonia of 2 D or greater 6 months after surgery. Nuclear sclerotic cataract has also been reported after vitrectomy for other diseases.7–11 After vitrectomy for macular hole, Thompson and associates6 reported progression to visually significant nuclear cataract in 45 (80%) of 56 eyes, and Takahashi et al12 reported an average myopic shift of 2.83 D. Melberg and Thomas13 found a high incidence (79%) of nuclear sclerosis in patients 50 years or older following vitrectomy for choroidal neovascularization. The cause of nuclear sclerosis after vitrectomy is not clearly known. However, we hypothesized that it could be prevented by minimal operative invasion of the eye. Therefore, we attempted to perform EMP surgery without intraocular irrigation or core vitrectomy. We have termed this procedure, nonvitrectomizing vitreous surgery.
Materials and Methods From December 1995 through June 1997, 21 patients with idiopathic EMP underwent unilateral nonvitrectomizing vitreous sur-
1541
Ophthalmology Volume 106, Number 8, August 1999 gery at our institution. Eyes chosen for surgery had epiretinal membranes within the temporal arcades and symptoms of visual loss or metamorphopsia. Patients who had undergone previous intraocular surgery or had a history of other ocular disorders in the EMP eye and patients with asymmetric lens opacities in the two eyes were excluded from the study. Eyes that had more than a mild degree of nuclear cataract were also excluded. We performed measurement of visual acuity, objective refraction with an automatic refractometer (Canon RK-2, Tokyo, Japan), and slit-lamp photography, both preoperatively and at the final postoperative examination. Scheimpflug photographs (Nidek EAS-1000, Aichi, Japan) were also taken in several patients. These examinations were performed on both eyes, with the nonoperative eye serving as a control for each patient. We compared the degree of preoperative and postoperative nuclear sclerosis in both eyes of each patient with slit-lamp photographs and/or Scheimpflug photographs. To eliminate the effect of aging on the progression of nuclear cataract, we also compared the degree of nuclear sclerosis between eyes. Lens opacities were graded according to the scale derived by Thompson and associates,6 summarized as follows: 0.0 – clear lens; 0.50 –trace cataract; 0.75–minimal cataract; 1.00 –mild cataract (all the above judged to have no effect on visual acuity); 2.00 –moderate cataract (judged to be decreasing visual acuity but allowing a good view of retina by contact lens biomicroscopy); 3.00 –moderately severe cataract (impairing visual acuity and causing some distortion or impairing the view of retina); and 4.00 –severe cataract (causing a very poor view of retina). The grades of nuclear sclerosis were statistically examined with chi-square or Fisher’s exact test if applicable. The spherical equivalent of the objective refractions measured at the preoperative and final postoperative examination were statistically examined with the paired-t test.
Surgical Technique The standard pars plana vitrectomy was modified as follows. Two sclerotomy sites (20 gauge or 23 gauge) were made 4 mm from the surgical limbus in the superotemporal and superonasal quadrant. An infusion port was not made in any of the cases. A fiberoptic light source and a microhooked needle14 were introduced through the sclerotomy sites. Removal of the membrane was initiated immediately, with no prior cutting of vitreous or other intraocular maneuvers. After the membrane was separated from the surface of the retina, it was left floating in the vitreous cavity in 11 patients (group 1) and removed from the eye in 10 patients (group 2). In the second group, the membrane was grasped with microforceps, pulled just through the sclerotomy site, and separated from the vitreous with microscissors. Incarcerated vitreous at the sclerotomy sites was cut with microscissors before sclerotomy closure. No solutions were injected into any of the study eyes, even when mild hypotony was noted.
Results We performed nonvitrectomizing vitreous surgery in 21 eyes of 21 patients with EMP. There were 5 men and 16 women, ranging in age from 51 to 77 years (mean, 62.0 years). We randomly assigned 11 eyes to group 1 (membrane left floating in the vitreous cavity), and 10 eyes to group 2 (membrane removed from the eye). The follow-up period ranged from 6 to 24 months (mean, 9.7 months). Nineteen of the 21 eyes had final visual acuity equal to or better than preoperative levels (Fig 1). There were no serious intraoperative complications during the study period. Minor complications occurring during surgery in-
1542
Figure 1. Preoperative visual acuity (VA) plotted against the final visual acuity. Group 1: membrane left floating in the vitreous cavity. Group 2: membrane removed from the eye.
cluded minimal bleeding from the surface of the retina into the preretinal space or vitreous cavity in 12 eyes. When hemorrhage from the retina was noted, the surgeon applied gentle digital compression to the globe. Hemorrhage disappeared by postoperative day 14 in all cases. Immediate postoperative hypotony was noted in all eyes, but this did not interfere with completion of the procedure, and the intraocular pressure normalized in all eyes by the first postoperative day. The majority of patients reported floaters during the immediate postoperative period, but 1 month after surgery only two patients in group 1 and one patient in group 2 reported persistence of floaters. This was despite that fact that membranes were still visible in the vitreous cavity in all group 1 patients on fundus examination (Fig 2). No retinal tears or retinal detachments occurred during the follow-up period. In four eyes (3 from group 1 and 1 from group 2), residual epimacular membranes were evident postoperatively, apparently obscured intraoperatively by preretinal hemorrhage. One patient with complaints of persistent metamorphopsia postoperatively, presumably caused by residual extrafoveal membrane, underwent repeat nonvitrectomizing surgery 3 months after the initial procedure. There was no difference in complications between group 1 and group 2 patients; however, the complaint of floaters was less frequent in group 2. During the follow-up period, 1 of 21 eyes had progression of nuclear cataract; however, the nonoperated fellow eye of this patient also developed nuclear cataract (Table 1). There was no significant difference in the degree of postoperative nuclear sclerosis between operated and nonoperated fellow eyes (Figs 3 and 4). As to the surgical subgroups, there was no significant difference in postoperative nuclear sclerosis between group 1 and group 2. There was no significant change in the spherical equivalent of the refractive error of the operated eyes between preoperative and final examination (Table 2). The nonoperated fellow eyes also revealed no significant difference (Table 2). There was no difference in refractive change between the surgical subgroups.
Discussion Nonvitrectomizing vitreous surgery under ordinary set-up was first described by Charles15 in 1987. He described membrane peeling and excision without removal of the vitreous in patients with EMP and small membranes but
Saito et al 䡠 Nonvitrectomizing Vitreous Surgery
Figure 2. Fundus photographs of a 58-year-old woman assigned to group 1. A, preoperatively, epimacular proliferation is present. B, postoperatively, the membrane has been separated from the neurosensory retina and is floating in the vitreous cavity. The patient reported only occasional awareness of floaters.
recommended core vitrectomy when membranes were larger and denser. Charles later abandoned nonvitrectomizing surgery because of initial postoperative floaters and vitreous opacities (personal communication, 1997). Some hypotheses have been proposed regarding the possible causes of postoperative nuclear sclerosis. Margherio and associates16 reported a relatively low incidence (12.5%) of nuclear cataract and attributed this finding to multiple factors, including shorter operating time, distance of the infusion port from the lens, type of irrigating fluid used, and a surgical technique that spared the anterior vitreous behind the lens. High glucose has been shown to cause nonenzymatic browning of lens proteins and cataract formation.17 de Bustros and associates18 found no significant difference in the incidence of nuclear sclerosis between two surgeons and that the high concentration of oxygen in the irrigating so-
Figure 3. Fundus and Scheimpflug photographs of a 67-year-old woman who underwent nonvitrectomizing EMP surgery in the right eye 18 months previously. The right lens remains clear and appears identical to the lens in the nonoperative left eye. RE ⫽ right eye; LE ⫽ left eye.
lution contributes to oxidation of lens proteins, which later may lead to an increase in fluorescent derivatives and development of nuclear cataract. Mitchell and Anderson19 showed that the antioxidant enzyme “catalase” can be inactivated in the presence of oxygen and light, and inactivation of antioxidant enzymes in the lens may further promote oxidation20 of the lens proteins, suggesting that intensive light exposure from an operating microscope can be a facilitating factor in nuclear cataract formation. Melberg and Thomas13 found the incidence of postvitrectomy nuclear sclerosis to be age related and limited primarily to patients over 50 years. Despite that fact that all of our patients were over the age of 50, none of them experienced a progression of nuclear sclerosis in the operated eye relative to the control eye during follow-up. Although the cause of nuclear sclerosis after vitrectomy is still unclear, nonvitrectomizing vitreous surgery seems to decrease its incidence. Although most patients in our series had floaters during the immediate postoperative period, only a few reported persistence of floaters 1 month after surgery, even when membranes were visible in the vitreous cavity. This is in contrast to the findings of Charles,15 as noted above. The sensation of floaters is the awareness of a moving shadow cast by a vitreous opacity onto the retina, and it depends on the distance between the opacity and the retina. When a posterior vitreous detachment occurs, patients are often initially very aware of the shadow caused by the presence of a Weiss ring. However, these symptoms typically quickly subside, as the vitreous collapses further. A similar phenomenon may occur after nonvitrectomizing surgery for EMP. Lack of infusion fluid led to immediate postoperative hypotony in all cases. Progressive hypotony during surgery may result in poor visualization, increased risk of lens touch by instruments passed through the sclerotomy sites, and suprachoroidal hemorrhage. Certain eyes, such as highly myopic eyes with more liquefied vitreous, may be especially prone to this complication. Fortunately, no hypotonyrelated complications occurred in our series. The degree of hypotony was limited by maintaining plugs or instruments in the sclerotomies at all times. Also, small amounts of
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Ophthalmology Volume 106, Number 8, August 1999
Figure 4. Scheimpflug photographs of a 70-year-old woman who underwent nonvitrectomizing EMP surgery in the right eye. Preoperatively, nuclear cataract grades were defined as 0.5 in both the right and left eyes. Postoperatively, there was no progression of nuclear sclerosis in either the operated right eye or the nonoperated left eye after 12 months of follow-up.
vitreous soon incarcerate in the sclerotomy sites, which also helps to maintain intraocular pressure. If severe hypotony occurs during nonvitrectomizing vitreous surgery, injection of a small amount of air or saline would probably be warranted to decrease the risk of complications. Another concern is the risk of retinal tears and postoperative retinal detachment resulting from intraoperative
traction on the vitreous in the absence of vitrectomy. We did not experience any of these complications, but careful examination of the retinal periphery at the completion of surgery is probably indicated after nonvitrectomizing vitreous surgery, just as it is after conventional vitrectomy. This is a preliminary study with a short follow-up period and a small sample size. However, our incidence of post-
Table 1. Change in Nuclear Sclerosis after Nonvitrectomizing Vitreous Surgery in Operative and Fellow Eyes of Two Groups of Patients with EMP* Preoperative Examination
Group 1 (peeling): 11 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0 Group 2 (removal): 10 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0 Total: 21 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0
Final Examination
Operated Eye
Fellow Eye
Operated Eye
Fellow Eye
1 8 2 0
1 8 2 0
1 7 2 1†
1 7 2 1†
1 6 3 0
1 6 3 0
1 6 3 0
1 6 3 0
2 14 5 0
2 14 5 0
2 13 5 1†
2 13 5 1†
EMP ⫽ epimacular proliferations. * Values listed reflect the grade of nuclear sclerosis at preoperative and final examinations. All patients had equal grades of nuclear sclerosis in their two eyes at preoperative examination. There was no significant difference in the development or progression of nuclear sclerosis between operated and fellow eyes by chi-square test or Fisher’s exact test. † One patient developed nuclear sclerosis from 0.5 to 1.0 in both eyes.
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Saito et al 䡠 Nonvitrectomizing Vitreous Surgery Table 2. Refractive Error before and after Nonvitrectomizing Vitreous Surgery in Operative and Fellow Eyes of Two Groups of Patients with EMP*
Group 1 (peeling): 11 eyes Preoperative Postoperative (final) Group 2 (removal): 10 eyes Preoperative Postoperative (final) Total cases: 21 eyes Preoperative Postoperative (final)
Operated Eyes (D)
Nonoperated Fellow Eyes (D)
0.86 ⫾ 2.44 0.84 ⫾ 2.50 NS
0.27 ⫾ 2.05 0.19 ⫾ 2.01 NS
0.60 ⫾ 3.24 0.51 ⫾ 3.26 NS
0.55 ⫾ 2.72 0.60 ⫾ 2.68 NS
0.74 ⫾ 2.78 0.68 ⫾ 2.81
0.40 ⫾ 2.34 0.34 ⫾ 2.32 NS
NS NS ⫽ not significant. * Average and standard deviation of the spherical equivalent of objective refraction is given in diopters. Comparison of preoperative and postoperative values with the paired t test showed no progression of myopia.
operative nuclear sclerosis was clearly lower than in previous studies in which infusion of fluid and removal of vitreous were used during surgery for EMP. Although nonvitrectomizing vitreous surgery cannot yet be recommended on the basis of this one small study, we believe our findings warrant further investigation. A larger prospective study with a longer follow-up period is needed to confirm the safety and efficacy of nonvitrectomizing vitreous surgery as a means of preventing the development or progression of nuclear sclerosis.
References 1. de Bustros S, Thompson JT, Michels RG, et al. Vitrectomy for idiopathic epiretinal membranes causing macular pucker. Br J Ophthalmol 1988;72:692–5. 2. Cherfan GM, Michels RG, de Bustros S, et al. Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker. Am J Ophthalmol 1991;111: 434 – 8. 3. Ogura Y, Takanashi T, Ishigooka H, Ogino N. Quantitative analysis of lens change after vitrectomy by fluorophotometry. Am J Ophthalmol 1991;111:179 – 83.
4. Kawakubo H, Sato Y, Shimada H, et al. Myopic change in refraction due to nuclear sclerotic change after vitreous surgery [Eng. abstr.]. Folia Ophthalmol Jpn 1996;47:396 – 400. 5. Ogura Y, Kitagawa K, Ogino N. Prospective longitudinal studies on lens changes after vitrectomy— quantitative assessment by fluorophotometry and refractometry [in Japanese]. Nippon Ganka Gakkai Zasshi 1993;97:627–31. 6. Thompson JT, Glaser BM, Sjaarda RN, Murphy RP. Progression of nuclear sclerosis and long-term visual results of vitrectomy with transforming growth factor beta-2 for macular holes. Am J Ophthalmol 1995;119:48 –54. 7. Smiddy WE, Michels RG, Glaser BM, de Bustros S. Vitrectomy for macular traction caused by incomplete vitreous separation. Arch Ophthalmol 1988;106:624 – 8. 8. Margherio RR, Trese MT, Margherio AR, Cartright K. Surgical management of vitreomacular traction syndromes. Ophthalmology 1989;96:1437– 45. 9. Van Effenterre G, Ameline B, Campinchi F, et al. La vitrectomie est-elle cataractoge`ne? Etude des modifications du cristallin apre`s chirurgie du de´collement de la re´tinc [Eng. abstr.] J Fr Ophtalmol 1992;15:449 –54. 10. McDonald HR, Johnson RN, Schatz H. Surgical results in the vitreomacular traction syndrome. Ophthalmology 1994;101: 1397– 403. 11. McDonald HR, Schatz H, Johnson RN, et al. Vitrectomy in eyes with peripheral retinal angioma associated with traction macular detachment. Ophthalmology 1996;103:329 –35. 12. Takahashi J, Akiba J, Fujio N, et al. Minus changes in refraction due to nuclear sclerosis after vitrectomy for idiopathic macular holes [Eng. abstr.]. Folia Ophthalmol Jpn 1997;48: 636 –9. 13. Melberg NS, Thomas MA. Nuclear sclerotic cataract after vitrectomy in patients younger than 50 years of age. Ophthalmology 1995;102:1466 –71. 14. Tano Y. Micro-hooked needle [In Japanese]. J Ophthalmic Surg 1988;1:313–5. 15. Charles S. Vitreous microsurgery, 2nd ed. Baltimore: Williams & Wilkins, 1987; 153–7. 16. Margherio RR, Cox MS Jr, Trese MT, et al. Removal of epimacular membranes. Ophthalmology 1985;92:1075– 83. 17. Stevens VJ, Rouzer CA, Monnier VM, Cerami A. Diabetic cataract formation: potential role of glycosylation of lens crystallins. Proc Natl Acad Sci U S A 1978;75:2918 –22. 18. de Bustros S, Thompson JT, Michels RG, et al. Nuclear sclerosis after vitrectomy for idiopathic epiretinal membranes. Am J Ophthalmol 1988;105:160 – 4. 19. Mitchell RL, Anderson IC. Catalase photoinactivation [report]. Science 1965;150:74. 20. Fecondo JV, Augusteyn RC. Superoxide dismutase catalase and glutathione peroxidase in the human cataractous lens. Exp Eye Res 1983;36:15–23.
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Originally received: June 30, 1998. Revision accepted: May 5, 1999. Manuscript no. 98348. From the Department of Ophthalmology, Osaka University Medical School, Suita, Japan. Presented in part at the Association for Research in Vision and Ophthalmology annual meeting, Fort Lauderdale, Florida, May 1998. Supported by the Grants-in-Aid for Scientific Research (#07557263) from the Ministry of Education, Science and Culture, and Health Science Research Grants, Japan. Address correspondence to Yoshihiro Saito, MD, Department of Ophthalmology, Hyogo Prefectural Nishinomiya Hospital, 13-9 Rokutanji, Nishinomiya 662-0918, Japan. E-mail: [email protected].
able marker for nuclear cataract, and found a significant increase 2 years after EMP vitrectomy. Kawakubo and associates4 used myopic shift as a marker for progression of nuclear sclerosis5,6 and found an average refractive change of 0.9 diopters (D) of myopia 6 months after vitrectomy for EMP. They also reported 11 (22%) of 50 patients had aniseikonia of 2 D or greater 6 months after surgery. Nuclear sclerotic cataract has also been reported after vitrectomy for other diseases.7–11 After vitrectomy for macular hole, Thompson and associates6 reported progression to visually significant nuclear cataract in 45 (80%) of 56 eyes, and Takahashi et al12 reported an average myopic shift of 2.83 D. Melberg and Thomas13 found a high incidence (79%) of nuclear sclerosis in patients 50 years or older following vitrectomy for choroidal neovascularization. The cause of nuclear sclerosis after vitrectomy is not clearly known. However, we hypothesized that it could be prevented by minimal operative invasion of the eye. Therefore, we attempted to perform EMP surgery without intraocular irrigation or core vitrectomy. We have termed this procedure, nonvitrectomizing vitreous surgery.
Materials and Methods From December 1995 through June 1997, 21 patients with idiopathic EMP underwent unilateral nonvitrectomizing vitreous sur-
1541
Ophthalmology Volume 106, Number 8, August 1999 gery at our institution. Eyes chosen for surgery had epiretinal membranes within the temporal arcades and symptoms of visual loss or metamorphopsia. Patients who had undergone previous intraocular surgery or had a history of other ocular disorders in the EMP eye and patients with asymmetric lens opacities in the two eyes were excluded from the study. Eyes that had more than a mild degree of nuclear cataract were also excluded. We performed measurement of visual acuity, objective refraction with an automatic refractometer (Canon RK-2, Tokyo, Japan), and slit-lamp photography, both preoperatively and at the final postoperative examination. Scheimpflug photographs (Nidek EAS-1000, Aichi, Japan) were also taken in several patients. These examinations were performed on both eyes, with the nonoperative eye serving as a control for each patient. We compared the degree of preoperative and postoperative nuclear sclerosis in both eyes of each patient with slit-lamp photographs and/or Scheimpflug photographs. To eliminate the effect of aging on the progression of nuclear cataract, we also compared the degree of nuclear sclerosis between eyes. Lens opacities were graded according to the scale derived by Thompson and associates,6 summarized as follows: 0.0 – clear lens; 0.50 –trace cataract; 0.75–minimal cataract; 1.00 –mild cataract (all the above judged to have no effect on visual acuity); 2.00 –moderate cataract (judged to be decreasing visual acuity but allowing a good view of retina by contact lens biomicroscopy); 3.00 –moderately severe cataract (impairing visual acuity and causing some distortion or impairing the view of retina); and 4.00 –severe cataract (causing a very poor view of retina). The grades of nuclear sclerosis were statistically examined with chi-square or Fisher’s exact test if applicable. The spherical equivalent of the objective refractions measured at the preoperative and final postoperative examination were statistically examined with the paired-t test.
Surgical Technique The standard pars plana vitrectomy was modified as follows. Two sclerotomy sites (20 gauge or 23 gauge) were made 4 mm from the surgical limbus in the superotemporal and superonasal quadrant. An infusion port was not made in any of the cases. A fiberoptic light source and a microhooked needle14 were introduced through the sclerotomy sites. Removal of the membrane was initiated immediately, with no prior cutting of vitreous or other intraocular maneuvers. After the membrane was separated from the surface of the retina, it was left floating in the vitreous cavity in 11 patients (group 1) and removed from the eye in 10 patients (group 2). In the second group, the membrane was grasped with microforceps, pulled just through the sclerotomy site, and separated from the vitreous with microscissors. Incarcerated vitreous at the sclerotomy sites was cut with microscissors before sclerotomy closure. No solutions were injected into any of the study eyes, even when mild hypotony was noted.
Results We performed nonvitrectomizing vitreous surgery in 21 eyes of 21 patients with EMP. There were 5 men and 16 women, ranging in age from 51 to 77 years (mean, 62.0 years). We randomly assigned 11 eyes to group 1 (membrane left floating in the vitreous cavity), and 10 eyes to group 2 (membrane removed from the eye). The follow-up period ranged from 6 to 24 months (mean, 9.7 months). Nineteen of the 21 eyes had final visual acuity equal to or better than preoperative levels (Fig 1). There were no serious intraoperative complications during the study period. Minor complications occurring during surgery in-
1542
Figure 1. Preoperative visual acuity (VA) plotted against the final visual acuity. Group 1: membrane left floating in the vitreous cavity. Group 2: membrane removed from the eye.
cluded minimal bleeding from the surface of the retina into the preretinal space or vitreous cavity in 12 eyes. When hemorrhage from the retina was noted, the surgeon applied gentle digital compression to the globe. Hemorrhage disappeared by postoperative day 14 in all cases. Immediate postoperative hypotony was noted in all eyes, but this did not interfere with completion of the procedure, and the intraocular pressure normalized in all eyes by the first postoperative day. The majority of patients reported floaters during the immediate postoperative period, but 1 month after surgery only two patients in group 1 and one patient in group 2 reported persistence of floaters. This was despite that fact that membranes were still visible in the vitreous cavity in all group 1 patients on fundus examination (Fig 2). No retinal tears or retinal detachments occurred during the follow-up period. In four eyes (3 from group 1 and 1 from group 2), residual epimacular membranes were evident postoperatively, apparently obscured intraoperatively by preretinal hemorrhage. One patient with complaints of persistent metamorphopsia postoperatively, presumably caused by residual extrafoveal membrane, underwent repeat nonvitrectomizing surgery 3 months after the initial procedure. There was no difference in complications between group 1 and group 2 patients; however, the complaint of floaters was less frequent in group 2. During the follow-up period, 1 of 21 eyes had progression of nuclear cataract; however, the nonoperated fellow eye of this patient also developed nuclear cataract (Table 1). There was no significant difference in the degree of postoperative nuclear sclerosis between operated and nonoperated fellow eyes (Figs 3 and 4). As to the surgical subgroups, there was no significant difference in postoperative nuclear sclerosis between group 1 and group 2. There was no significant change in the spherical equivalent of the refractive error of the operated eyes between preoperative and final examination (Table 2). The nonoperated fellow eyes also revealed no significant difference (Table 2). There was no difference in refractive change between the surgical subgroups.
Discussion Nonvitrectomizing vitreous surgery under ordinary set-up was first described by Charles15 in 1987. He described membrane peeling and excision without removal of the vitreous in patients with EMP and small membranes but
Saito et al 䡠 Nonvitrectomizing Vitreous Surgery
Figure 2. Fundus photographs of a 58-year-old woman assigned to group 1. A, preoperatively, epimacular proliferation is present. B, postoperatively, the membrane has been separated from the neurosensory retina and is floating in the vitreous cavity. The patient reported only occasional awareness of floaters.
recommended core vitrectomy when membranes were larger and denser. Charles later abandoned nonvitrectomizing surgery because of initial postoperative floaters and vitreous opacities (personal communication, 1997). Some hypotheses have been proposed regarding the possible causes of postoperative nuclear sclerosis. Margherio and associates16 reported a relatively low incidence (12.5%) of nuclear cataract and attributed this finding to multiple factors, including shorter operating time, distance of the infusion port from the lens, type of irrigating fluid used, and a surgical technique that spared the anterior vitreous behind the lens. High glucose has been shown to cause nonenzymatic browning of lens proteins and cataract formation.17 de Bustros and associates18 found no significant difference in the incidence of nuclear sclerosis between two surgeons and that the high concentration of oxygen in the irrigating so-
Figure 3. Fundus and Scheimpflug photographs of a 67-year-old woman who underwent nonvitrectomizing EMP surgery in the right eye 18 months previously. The right lens remains clear and appears identical to the lens in the nonoperative left eye. RE ⫽ right eye; LE ⫽ left eye.
lution contributes to oxidation of lens proteins, which later may lead to an increase in fluorescent derivatives and development of nuclear cataract. Mitchell and Anderson19 showed that the antioxidant enzyme “catalase” can be inactivated in the presence of oxygen and light, and inactivation of antioxidant enzymes in the lens may further promote oxidation20 of the lens proteins, suggesting that intensive light exposure from an operating microscope can be a facilitating factor in nuclear cataract formation. Melberg and Thomas13 found the incidence of postvitrectomy nuclear sclerosis to be age related and limited primarily to patients over 50 years. Despite that fact that all of our patients were over the age of 50, none of them experienced a progression of nuclear sclerosis in the operated eye relative to the control eye during follow-up. Although the cause of nuclear sclerosis after vitrectomy is still unclear, nonvitrectomizing vitreous surgery seems to decrease its incidence. Although most patients in our series had floaters during the immediate postoperative period, only a few reported persistence of floaters 1 month after surgery, even when membranes were visible in the vitreous cavity. This is in contrast to the findings of Charles,15 as noted above. The sensation of floaters is the awareness of a moving shadow cast by a vitreous opacity onto the retina, and it depends on the distance between the opacity and the retina. When a posterior vitreous detachment occurs, patients are often initially very aware of the shadow caused by the presence of a Weiss ring. However, these symptoms typically quickly subside, as the vitreous collapses further. A similar phenomenon may occur after nonvitrectomizing surgery for EMP. Lack of infusion fluid led to immediate postoperative hypotony in all cases. Progressive hypotony during surgery may result in poor visualization, increased risk of lens touch by instruments passed through the sclerotomy sites, and suprachoroidal hemorrhage. Certain eyes, such as highly myopic eyes with more liquefied vitreous, may be especially prone to this complication. Fortunately, no hypotonyrelated complications occurred in our series. The degree of hypotony was limited by maintaining plugs or instruments in the sclerotomies at all times. Also, small amounts of
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Ophthalmology Volume 106, Number 8, August 1999
Figure 4. Scheimpflug photographs of a 70-year-old woman who underwent nonvitrectomizing EMP surgery in the right eye. Preoperatively, nuclear cataract grades were defined as 0.5 in both the right and left eyes. Postoperatively, there was no progression of nuclear sclerosis in either the operated right eye or the nonoperated left eye after 12 months of follow-up.
vitreous soon incarcerate in the sclerotomy sites, which also helps to maintain intraocular pressure. If severe hypotony occurs during nonvitrectomizing vitreous surgery, injection of a small amount of air or saline would probably be warranted to decrease the risk of complications. Another concern is the risk of retinal tears and postoperative retinal detachment resulting from intraoperative
traction on the vitreous in the absence of vitrectomy. We did not experience any of these complications, but careful examination of the retinal periphery at the completion of surgery is probably indicated after nonvitrectomizing vitreous surgery, just as it is after conventional vitrectomy. This is a preliminary study with a short follow-up period and a small sample size. However, our incidence of post-
Table 1. Change in Nuclear Sclerosis after Nonvitrectomizing Vitreous Surgery in Operative and Fellow Eyes of Two Groups of Patients with EMP* Preoperative Examination
Group 1 (peeling): 11 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0 Group 2 (removal): 10 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0 Total: 21 eyes Grade 0.0 Grade 0.5 Grade 0.75 Grade 1.0
Final Examination
Operated Eye
Fellow Eye
Operated Eye
Fellow Eye
1 8 2 0
1 8 2 0
1 7 2 1†
1 7 2 1†
1 6 3 0
1 6 3 0
1 6 3 0
1 6 3 0
2 14 5 0
2 14 5 0
2 13 5 1†
2 13 5 1†
EMP ⫽ epimacular proliferations. * Values listed reflect the grade of nuclear sclerosis at preoperative and final examinations. All patients had equal grades of nuclear sclerosis in their two eyes at preoperative examination. There was no significant difference in the development or progression of nuclear sclerosis between operated and fellow eyes by chi-square test or Fisher’s exact test. † One patient developed nuclear sclerosis from 0.5 to 1.0 in both eyes.
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Saito et al 䡠 Nonvitrectomizing Vitreous Surgery Table 2. Refractive Error before and after Nonvitrectomizing Vitreous Surgery in Operative and Fellow Eyes of Two Groups of Patients with EMP*
Group 1 (peeling): 11 eyes Preoperative Postoperative (final) Group 2 (removal): 10 eyes Preoperative Postoperative (final) Total cases: 21 eyes Preoperative Postoperative (final)
Operated Eyes (D)
Nonoperated Fellow Eyes (D)
0.86 ⫾ 2.44 0.84 ⫾ 2.50 NS
0.27 ⫾ 2.05 0.19 ⫾ 2.01 NS
0.60 ⫾ 3.24 0.51 ⫾ 3.26 NS
0.55 ⫾ 2.72 0.60 ⫾ 2.68 NS
0.74 ⫾ 2.78 0.68 ⫾ 2.81
0.40 ⫾ 2.34 0.34 ⫾ 2.32 NS
NS NS ⫽ not significant. * Average and standard deviation of the spherical equivalent of objective refraction is given in diopters. Comparison of preoperative and postoperative values with the paired t test showed no progression of myopia.
operative nuclear sclerosis was clearly lower than in previous studies in which infusion of fluid and removal of vitreous were used during surgery for EMP. Although nonvitrectomizing vitreous surgery cannot yet be recommended on the basis of this one small study, we believe our findings warrant further investigation. A larger prospective study with a longer follow-up period is needed to confirm the safety and efficacy of nonvitrectomizing vitreous surgery as a means of preventing the development or progression of nuclear sclerosis.
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