The Results of Nation-Wide Registry of Age-related Macular Degeneration in Korea

PURPOSE: To evaluate the incidence and clinical features of age-related macular degeneration (AMD) in Korea. METHODS: Web-based (www.armd-nova.or.kr) registration was conducted for AMD patients aged 50 or more who were newly diagnosed by retinal specialists in Korea from August 20, 2005 to August 20, 2006. Patient data including ophthalmologic examination, fundus photography, fluorescein angiogram and/or indocyanin green angiogram (ICG), past medical history, behavioral habit, combined systemic diseases were up-loaded. RESULTS: Among finally enrolled 1,141 newly diagnosed AMD patients, 690 patients (60.5%) were male and 451 patients (39.5%) were female. The average age of AMD patients was 69.7+/-8.0. Early AMD was observed in 190 patients and 951 patients had late AMD. Classic choroidal neovascular membrane (CNVM) was observed in 18.6% of exudative AMD patients and 63.4 % had occult CNVM. Subfoveal CNVM was observed in 80.4% of the patients with CNVM. Among the 580 exudative AMD eyes that performed indocyanin green angiography (ICG), 184 eyes (31.7%) had polypoidal choroidal vasculopathy (PCV) and 36 eyes (6.2%) showed retinal angiomatous proliferation (RAP). Age, male gender, smoking, diabetes and hypertension significantly increased the risk of the AMD among Koreans. CONCLUSIONS: Because of the low rate of participation by retinal specialists, definite incidence of AMD was not obtainable. However, the estimated 1-year AMD incidence in the Pusan area of Korea is at least 0.4%. In contrast to Western people, 31.7% of exudative AMD cases were revealed to be PCV and 6.2% were revealed to be RAP. This discrepancy between ethnic groups should be considered in the diagnosis and treatment modality selection of Korean AMD patients.

Topical and Oral Voriconazole in the Treatment of Fungal Keratitis

We describe two patients with fungal keratitis refractory to standard antifungal therapy whose conditions were managed with voriconazole. The first case is a patient with endophthalmitis and corneal ulcer due to Candida parapsilosis after receiving a corneal transplant. The patient was treated with amphotericin but showed no signs of improvement. Topical voriconazole, oral voriconazole, and intravitreal voriconazole yielded signs of improvement. The second case is a 63-year-old male who underwent a month of empiric treatment with 0.2% topical amphotericin for fungal keratitis but showed no signs of improvement. Treatment was then provided with 1% voriconazole. Both cases showed effective treatment with voriconazole. Voriconazole may be considered as a new method to treat fungal keratitis refractory to standard antifungal therapy.

Two Cases of Branch Retinal Arterial Occlusion After Carotid Artery Stenting in the Carotid Stenosis

We describe two cases of branch retinal artery occlusion (BRAO) after carotid artery (CA) stenting. Case 1: A 57-year-old man diagnosed with left neovascular glaucoma was admitted to our department for trabeculectomy (He had complained of decreased visual acuity (VA) in the left eye for a month). A preoperative neck angio CT scan showed bilateral CA stenosis. After CA stenting, he contracted visual defects on the right superior area of his right eye. Upon examination, VA with correction was found to be 1.0 (OD), but right fundoscopy revealed ischemic retina whitening along the inferior temporal arcade. Case 2: A 64-year-old man received left CA stenting for severe stenosis in the Department of Neurology. The next day, he was referred to us for acute onset of a left naso-inferior visual field defect. Upon initial examination, his VA with correction was 0.8/0.16 (OD/OS) and fundoscopy revealed ischemic retina whitening at the superior posterior pole in the left eye. It was not necessary to treat the BRAO in these cases because the foveal capillary network was not invaded at 2 month follow ups, VA was preserved in both cases. In conclusion, ophthalmic evaluation is important after CA stenting because of a possible embolic occlusion of the retinal artery.

Clinical Outcomes After Intraocular Silicone Oil Removal and Analysis of Its Prognostic Factors

PURPOSE: To evaluate the factors influencing clinical outcome after removal of intraocular silicone oil and the relationship of the factors to the postoperative visual prognosis. METHODS: The authors retrospectively analyzed clinical outcomes related to 76 patients (79 eyes) who underwent silicone oil tamponade. Prognostic factors were as follows: age, underlying pathologies, systemic diseases, range and type of retinal detachment (RD), type of RD, number of retinal tears, macular and lens status, and types of operation. The influence of these factors on visual acuity and anatomical success rates were studied. RESULTS: The 79 eyes that underwent silicone oil removal had preoperative diagnoses as follows: proliferative diabetic retinopathy in 32 eyes, primary rhegmatogenous RD in 12 eyes, RD with an intraocular foreign body in nine eyes, traumatic RD in eight eyes, RD with a macular hole in six eyes, RD development after other surgeries in six eyes, RD with endophthalmitis in three eyes, and RD with high myopia in three eyes. Anatomical success was achieved in 59 eyes (74.7%) after silicone oil removal. Thirty-two eyes (40.5%) had an increase in visual acuity, 28 eyes (35.4%) showed no changes and 19 eyes (24.1%) showed deteriorated conditions after silicone oil removal. The number of surgeries was an important factor related to anatomical and functional success rate. Postoperative visual improvement was observed when the number of surgeries was greater than two and in groups with no macular holes or degenerations. CONCLUSIONS: When considering prognostic factors for silicone oil removal, reducing complications and retinal redetachment after silicone oil removal may be helpful.

Intravitreal Bevacizumab (Avastin) Treatment of Neovascular Glaucoma in Ocular Ischemic Syndrome

We report a case of ocular ischemic syndrome accompanied by neovascular glaucoma that was successfully treated with Bevacizumab. A 70-year-old male patient diagnosed with neovascular glaucoma of the left eye 3-4 years prior complained of continuous left eye pain and declining visual acuity despite receiving the latest treatment methods. At the time of admission the patient had no light perception in the left eye and his intraocular pressure was 30 mmHg. Anterior segment and fundus examinations revealed neovascularization of the iris and stenosis of the retinal vessel. Hypofluorescence of the choroid and retinal vessels was observed on fluorescence fundus angiography. Left internal carotid artery stenosis was observed on a brain MRI. Despite being treated with eye solution and oral medication, intraocular pressure was not controlled. After 7 days, we performed an intravitreal Bevacizumab 1.25 mg/0.05mL injection. One day after the intravitreal Bevacizumab injection, the neovascularization had nearly regressed and intraocular pressure was 30 mmHg. Intravitreal Bevacizumab injection produced regression of neovascularization and proved effective for treatment of neovascular glaucoma in this case of ocular ischemic syndrome.

Intravitreal Bevacizumab (Avastin) Treatment of Neovascular Glaucoma in Ocular Ischemic Syndrome

We report a case of ocular ischemic syndrome accompanied by neovascular glaucoma that was successfully treated with Bevacizumab. A 70-year-old male patient diagnosed with neovascular glaucoma of the left eye 3-4 years prior complained of continuous left eye pain and declining visual acuity despite receiving the latest treatment methods. At the time of admission the patient had no light perception in the left eye and his intraocular pressure was 30 mmHg. Anterior segment and fundus examinations revealed neovascularization of the iris and stenosis of the retinal vessel. Hypofluorescence of the choroid and retinal vessels was observed on fluorescence fundus angiography. Left internal carotid artery stenosis was observed on a brain MRI. Despite being treated with eye solution and oral medication, intraocular pressure was not controlled. After 7 days, we performed an intravitreal Bevacizumab 1.25 mg/0.05mL injection. One day after the intravitreal Bevacizumab injection, the neovascularization had nearly regressed and intraocular pressure was 30 mmHg. Intravitreal Bevacizumab injection produced regression of neovascularization and proved effective for treatment of neovascular glaucoma in this case of ocular ischemic syndrome.

Kimura's Disease Involving the Ipsilateral Face and Extraocular Muscles

Kimura's disease (KD) is a rare, chronic inflammatory disorder, which is characterized by tumor-like masses mainly located in the head and neck region. Extraocular muscle involvement in KD is uncommon. We report a case of KD that involved both the extraocular muscles and buccal area. A 13-year-old male presented to our clinic with a two-year history of exophthalmos of the left eye and facial swelling. Facial CT and MRI showed a 1.5 x 1.5 cm2 soft tissue mass located at the left masticator and buccal area, exophthalmos of the left eye, and diffuse thickening of the left extraocular muscles. We performed a lateral rectus muscle incisional biopsy of the left eye. Oral methylprednisolone therapy was initiated and tapered following the incisional biopsy.

Prevalence of Myopia in 19-Year-Old Men in Gyeongsangnam-do, Ulsan and Busan in 2002

PURPOSE: To investigate the prevalence of myopia and its influencing factors in an epidemiologic study of conscripts living in Gyeongsangnam-do, Ulsan and Busan. METHODS: A cross-sectional study was conducted in 19-year-old conscripts in Gyeongsangnam-do, Ulsan and Busan. Health checkup data of the conscripts were collected and analyzed along with subjective visual acuity, noncycloplegic autorefraction test, biometric data, and social factors such as education level and residence area. Myopia and high myopia were defined as having a refractive error of more than -0.5D, -6.0D, respectively. To analyze the social and biometric effects, we classified social factors into three groups and biometric factors into five groups. The estimated myopic prevalence was calculated adding excluded conscripts who scored under 0.5 on the subjective visual acuity test and missed autorefraction data. Data analysis was performed with descriptive analysis and the chi square test for trends using the Statistical Package for the Social Sciences (SPSS) version 14.0K. RESULTS: From 66,917 eligible conscripts, 50,243 were analyzed. The prevalence of myopia and high myopia in 19-year-old men in Gyeongsangnam-do, Ulsan and Busan were 45.60% (95% CI: 45.17~46.03) and 11.50% (95% CI: 11.23~11.77). The estimated myopic prevalence using 66,917 eligible conscripts was 54.31% (95% CI: 53.88~54.74). CONCLUSIONS: The prevalence of myopia and high myopia and the estimated prevalence of myopia in 19-year-old men in Gyeongsangnam-do, Ulsan and Busan were 45.60%, 11.50% and 54.31%, respectively.

Black Diaphragm Intraocular Lens for Traumatic Aniridia: Long-term Follow-up

PURPOSE: This is a report on the long-term follow-up of patients who had received black diaphragm intraocular lens implantation after traumatic aniridia. METHODS: This is a retrospective study on the long-term follow-up for more than 50 months of six patients who had received black diaphragm intraocular lens implantation after traumatic aniridia. RESULTS: An improvement in visual acuity of more than two letters, according to the Snellan chart, occurred in three out of six eyes that were available for follow-up studies after an average period of 7 years and 8 months (50-115 months) after the operation, and no visual acuity decline groups were present. Early complications of black diaphragm intraocular lens implantation consisted of cystoid macular edema and transient intraocular pressure rise. The complications late occurred included bullous keratopathy in four eyes, glaucoma in three eyes, and exotropia in three eyes. We performed penetrating keratoplasty in two of the four eyes suffering from bullous keratopathy, and an Ahmed valve implantation in two of the three eyes suffering from glaucoma. There were signs of reduced visual acuity in four eyes due to complications of the surgery. CONCLUSIONS: The authors of this report recommend care in use of black diaphragm intraocular lens implantation, by studies done with an average follow-up period of 7 years and 8 months post operatively. Also reported were severe complications with this treatment such as bullous keratopathy and glaucoma.

A Case of Diode Laser Photocoagulation in the Treatment of Choroidal Metastasis of Breast Carcinoma

To report a single case of improvement on choroidal metastasis of breast cancer after laser photocoagulation. A 52-year-old female patient who complained of visual disturbance of the right eye with multiple states of metastasis of breast carcinoma. On initial examination, the right best-corrected visual acuity was 0.63. Right fundoscopy revealed an elevated mass-like lesion temporal to the macule with serous retinal detachment. The mass had a 3.5-disc diameter. A right fluorescein angiogram revealed hypofluorescence during the prearterial and arteriovenous phase and hyperfluorescence during the venous phase. The venous phase showed almost total masking of background choroidal fluorescence at the elevated lesion because of leakage and neovascularization. The patient was treated 4 times by diode laser photocoagulation in addition to chemotherapy. Fifty days after the diode laser treatments, the funduscopy examination and fluorescein angiogram revealed that the serous retinal detachment had been absorbed, the choroid had become flat, the lesion had been reduced in size and hyperfluorescence. The right best-corrected visual acuity was improved to 0.8. Laser photocoagulation appears not to cause any problems for the patient and may be an efficient treatment for patients with choroidal breast carcinoma.

The Effect of Intravitreal Triamcinolone Acetonide on Intraocular Pressure in Uveitis

PURPOSE: We performed a retrospective study to investigate intraocular pressure (IOP) changes after an intravitreal triamcinolone acetonide (IVTA) in uveitic patients and to compare them with those of other diseases. METHODS: We reviewed 12 patients (17 eyes) who were diagnosed with uveitis and treated by oral and topical steroid, and then triamcinolone acetonide injection into the vitreous cavity in our hospital from March 2003 to April 2005. We evaluated IOP changes of uveitic patients and compared them with those of diabetic retinopathy (DR, 21 eyes), branch retinal vein occlusion (BRVO, 11 eyes), and age-related macular degeneration (AMD, five eyes) who were also treated by IVTA. RESULTS: The elevation of IOP (p=0.042) and maximum IOP (p=0.003) were statistically significantly different in uveitic patients compared to those in other patients (DR, BRVO, and AMD). The mean age was not statistically significantly different between the IOP elevated group and not-elevated group in uveitic patients, although IOP was significantly increased in patients over 40 years old (p=0.04). IOP was more elevated in uveitic patients with a short attack duration (p=0.03). The duration required for developing an elevated IOP ranged from one to ten weeks after IVTA treatment in uveitic patients, and two eyes received glaucoma surgery because of poorly controlled IOP. CONCLUSIONS: IVTA in uveitc patients is a useful method to reduce inflammation, but IOP elevation is more common in uveitc patients than in other disease (DR, BRVO, AMD), and may develop until ten weeks after treatment, so an extended follow-up schedule is recommended.

Multiple Retinal Hemorrhage following Anterior Chamber Paracentesis in Uveitic Glaucoma

PURPOSE: We describe the occurrence of a massive retinal hemorrhage following anterior chamber paracentesis in uveitic glaucoma. METHODS: A 33-year-old man who suffered from uveitic glaucoma was transferred to our hospital. The IOP in both his eyes was documented to vary between 11 mmHg and 43 mmHg and remained at a continuously high level for 7 months despite maximally tolerable medical treatment. A paracentesis was performed bilaterally to lower the IOP. RESULTS: Immediately after the paracentesis, massive retinal hemorrhages occurred in the left eye. Multiple round blot retinal hemorrhages with white centers occurred in the equator and peripheral retina, and small slit hemorrhages were observed in the peripapillary area. A fluorescence angiography(FAG) showed no obstruction of retinal vessels but a slightly delayed arteriovenous time in the left eye. CONCLUSIONS: It is important to be aware that patients who have a persistent relatively high IOP are at an increased risk of developing decompression retinopathy due to paracentesis and filtering surgery.

The Use of Ultrasonography for Detection of Retinal Detachment in Patients with Vitreous Hemorrhage

PURPOSE: This study aimed to determine the accuracy of ultrasonography (US) in detecting retinal detachment in vitreous hemorrhage (V-HEMO). METHODS: A chart review of 81 patients (86 eyes) who have undergone pars plana vitrectomy in the treatment of V-HEMO between June 1996 and June 2004 was done. RESULTS: The most common cause of vitreous hemorrhaging was proliferative diabetic retinopathy (PDR) (39 eyes, 45.3%), followed by ocular trauma (22 eyes, 25.6%). the correct anatomic position of the retina was identified with US in 72 of 86 eyes (83.7%), with eight false positives (9.3%) and six false negatives(7.9%). The sensitivity of US was calculated as 73% and specificity was 88%. US within the PDR group correctly identified 29 of 39 eyes (74.4%), and had a sensitivity of 62% and a specificity of 81%. US within the non-PDR group correctly identified 43 of 47 eyes (91.5%), and had a sensitivity of 89% and a specificity of 92%. CONCLUSIONS: It has been reported that US is an effective diagnostic tool in patients with media opacity, however physicians should bear in mind that US can be unreliable in some patients with PDR. Thus, caution is warranted in making diagnoses and determining the appropriated surgical procedure.

Prognostic Factors of Visual Acuity in Diabetes Mellitus

PURPOSE: We performed a retrospective study to investigate the risk factors for visual prognosis in diabetes mellitus patients. METHODS: We reviewed 179 patients (358 eyes) who visited our hospital from January 1990 to January 2004. RESULTS The final visual outcome showed improvement in 28 (7.8%) eyes, no change in 193 (53.9%) eyes and worsening in 137 (38.3%) eyes. Duration of diabetes mellitus (p=0.01), diabetic retinopathy (p=0.001), higher grade diabetic retinopathy (p=0.002), progression of cataract (p=0.002), glaucoma (p=0.011), control of hypertension (p=0.001) and an abnormally low glomerular filtration rate (p=0.004) were all indicative of a high risk for decreased visual acuity. But other factors (age, type of diabetes mellitus, abnormality of electrocardiography, HbA1c, serum lipid) were not significantly correlated with visual prognosis (p>0.05). CONCLUSIONS: We concluded that duration of diabetes mellitus, diabetic retinopathy, higher grade diabetic retinopathy, cataract, glaucoma, control of hypertension and abnormally low glomerular filtration rate were the risk factors of decreased visual acuity.

Prognostic Factors of Visual Acuity in Diabetes Mellitus

PURPOSE: We performed a retrospective study to investigate the risk factors for visual prognosis in diabetes mellitus patients. METHODS: We reviewed 179 patients (358 eyes) who visited our hospital from January 1990 to January 2004. RESULTS The final visual outcome showed improvement in 28 (7.8%) eyes, no change in 193 (53.9%) eyes and worsening in 137 (38.3%) eyes. Duration of diabetes mellitus (p=0.01), diabetic retinopathy (p=0.001), higher grade diabetic retinopathy (p=0.002), progression of cataract (p=0.002), glaucoma (p=0.011), control of hypertension (p=0.001) and an abnormally low glomerular filtration rate (p=0.004) were all indicative of a high risk for decreased visual acuity. But other factors (age, type of diabetes mellitus, abnormality of electrocardiography, HbA1c, serum lipid) were not significantly correlated with visual prognosis (p>0.05). CONCLUSIONS: We concluded that duration of diabetes mellitus, diabetic retinopathy, higher grade diabetic retinopathy, cataract, glaucoma, control of hypertension and abnormally low glomerular filtration rate were the risk factors of decreased visual acuity.

A Case of the Sclera-fixated Intraocular Lens with Haptic Fracture Developed After Rubbing the Eye

PURPOSE: We report one case of the sclera-fixated posterior chamber intraocular lens in which haptic fracture developed after rubbing the eye. METHODS: A 72-year-old man visited our clinic because of diminished vision in his right eye after rubbing the eye. Four years previously, the posterior capsule was ruptured and the nucleus dropped into the vitreous cavity during phacoemusification at another hospital. The patient was transferred to our hospital where vitrectomy, lens nucleus removal and scleral fixation using a PMMA intraocular lens were performed. RESULTS: The uncorrected visual acuity was finger count 30cm in the right eye and 0.8 in the left eye, and best-corrected visual acuity was 0.6 in the right eye. A dislocated intraocular lens was found at the inferonasal peripheral area in the vitreous cavity. The dislocated intraocular lens was removed through the corneal wound using injection of perfluorocarbon into the vitreous cavity, and then a PMMA intraocular lens with a haptic ring was inserted by scleral fixation. The haptic of the dislocated intraocular lens fixed at the superotemporal region had broken and a rough plane revealed in the electromicroscopic finding. We considered that impact rather than friction caused the haptic to break.

Comparative Evaluation of Radial Optic Neurotomy and Panretinal Photocoagulation in the Management of Central Retinal Vein Occlusion

PURPOSE: There is currently no treatment proven effective for central retinal vein occlusion (CRVO). Radial optic neurotomy (RON) has recently surfaced as a new treatment for the disorder, however, and we compare here the visual acuity (VA) and arteriovenous transit time (AVTT) following RON and panretinal photocoagulation (PRP). METHODS: We conducted a retrospective, uncontrolled study of 27 patients. Of 27 eyes diagnosed with CRVO, 16 were treated with panretinal photocoagulation (PRP) and 11 with RON. VA and fluorescein angiography were used to monitor the evolution of CRVO, and for follow-up. RESULTS: All patients underwent PRP or RON with no major complications. The difference between pre- and post-operative VA was not statistically significant for either group (p=0.092 on PRP; p=.0081 on RON). The change in AVTT was also not statistically significant for either group (p=0.024 on PRP; p=0.027 on RON). Ultimately, we found no statistically-significant difference in comparing VA and AVTT for the two groups (p=0.074 on VA; p=0.510 on AVTT). CONCLUSIONS: No evidence supporting the effectiveness of RON could be found in this study, suggesting that surgical decompression by RON may not be effective for treating CRVO. Further studies regarding the efficacy of RON should be made.

Clinical Evaluation of Radiation Retinopathy

PURPOSE: To assess variable clinical findings and risk factors of radiation retinopathy and to evaluate the effects of laser photocoagulation. METHODS: We reviewed the medical charts of 55 patients who received fractionated external-beam radiation during the treatment of head and neck tumors and who had a minimum of 2 years of follow-up from January 1996 to June 2002. RESULTS: Thirteen eyes in 8 patients developed radiation retinopathy. The mean time to the onset of symptoms attributable to retinal ischemia was 28 months (range, 15 to 43 months). The most common initial visual symptom was decreased visual acuity. Retinal hemorrhages, hard exudates and cotton wool spots were frequently observed fundus findings, and capillary non-perfusion on fluorescein angiography was the invariable findings. The mean total radiation dose was significantly higher in the retinopathy positive group (66.9+/-5.7 Gy) than in the retinopathy negative group (55.4+/-15.8 Gy) (P<0.05). Laser photocoagulation was performed in nine eyes of which 7 had good prognosis for retaining and regaining good central vision at the last follow-up. CONCLUSIONS: Although radiation retinopathy is infrequent, the long-term visual outcome is good with adequate laser photocoagulation treatment when detected early by close and regular follow-up.

The Postoperative Results and the Risk Factors Between Removed and Retained Intraocular Foreign Bodies

PURPOSE: This study was designed to compare the results and prognosis between the two groups; the removed (group A) and retained (group B). The factors which affect the final vision were also studied. METHODS: 57 eyes of 57 patients (56 male, mean age 36.3 years old) who had been managed for intraocular foreign bodies were divided in two; Group A 39 eyes, Group B 18 eyes. To determine prognostic factors for visual outcomes, variables including age of patient, visual acuity at first examination, kind and size of foreign body, site of penetration, intraocular location, timing and number of surgical session, and complications were compared with final visual acuity. RESULTS: The average follow up period was 26.8 months. During these period, the mean number of surgical treatment was 2.32 +/- 1.14 per one eye for primary closure or management of complications and sequelae. The risk factors which affect the final vision were initial visual acuity (p=0.000), size (p=0.012), number of surgical session (p=0.021) and retinal detachment (p=0.001), while others including age, kind, entry site, location, surgical timing and endophthalmitis showed no significance. There are no significant difference of anatomical and functional outcome between Group A and B, and there are no significant determinants among prognostic factors affecting final visual acuity between Group A and B. CONCLUSIONS: Traumatic intraocular foreign bodies require early surgical removal and adequate management. However, our study suggests the final visual acuity correlates best with the extent of damage at the time of the initial injury, and the presence of an intraocualr foreign body doesn't affect the visual prognosis when compared to cases without a foreign body.

The Effects of Growth Factors on the Contractility of Muller Cells

PURPOSE: To assess the ability of retinal Muller cells that are to generate tractional forces during culture and to evaluate their responsiveness to contraction-stimulating growth factors. METHODS: After being dissociated from porcine retina, Muller cells were cultured, and identified by immunocytochemistry. The cells were applied to the collagen gel, and changes in the thickness of the collagen layer over time were measured. Then these values were used to estimate Muller cell's contractility indirectly. Each of the applications was classified by an initial cell population and added IGF-I and PDGF concentrations. RESULTS: The contraction rate of collagen at 24 hours into incubation differed significantly between the cell groups, with group 1 having a ratio of 5.08 +/- 0.81, group 2; 7.96 +/- 0.44, group 3; 21.46 +/- 0.86, and group 4; 28.36 +/- 1.64% (p=0.000). The contraction rate of the IGF-treated groups and the PDGF-treated groups are increased by their concentrations (P<0.05), and the contraction rate of the IGF-treated groups was higher than the PDGF-treated groups at all concentration (P<0.05). CONCLUSIONS: As the cell number and concentration of growth factors were increased, the contractility of Muller cells was elevated. The development of neutralizing antibody to IGF-I and PDGF can be one of the ways for prevention of proliferative vitreoretinopathy clinically.