Peripheral Retinal Lesions Observed after Preoperative Evaluation for LASIK

PURPOSE: We estimated the incidence of retinal lesions at preoperative evaluation of retina for LASIK and investigate its clinical importance. METHODS: We estimated retrospectively the incidence of retinal lesions of the patients who visited our hospital with the purpose of correction of refractive error. The examination of retina upto periphery was done preoperatively. RESULTS: The mean spherical value and axial length were -6.5 +/- 3.4 diopters (range -26.0 ~ +17.0) and 25.4 +/- 2.0mm (range 15.7 ~ 34.5), respectively. The retinal lesions were found in 189 eyes of 139 persons (12.4%). Among them degenerative changes were found in 48 eyes of 34 persons, chorioretinal scars in 7 eyes of 7 persons, pigmented lesions in 28 eyes of 24 persons, and miscellaneous lesions in 106 eyes of 74 persons. There was a significant increase of spherical value and axial length in the group with retinal lesions -7.9 +/- 4.5 diopters (range -26.00 ~ -2.25), 26.5 +/- 2.3mm (range 23.1 ~ 34.5) compared to that without retinal lesions -6.1 +/- 3.4 diopters (range -25.00 ~ 17.00), 25.4 +/- 2.1mm (range 15.7 ~ 35.4). And the incidence of degenerative change and retinal tear was significantly increased in moderate myopes more than -4 diopters. CONCLUSIONS: LASIK is relatively a kind of safe refractive surgery, but to prevent the unexpected postoperative retinal complications, it is essential to thoroughly examine the retina upto periphery before surgery.

The Surgical Outcome of Clear Lens Extraction in High Myopia

PURPOSE: The authors evaluated the clinical results, the degree of satisfaction regarding daily activities and the quality of life after clear lens extraction in high myopes. METHODS: Thirty nine eyes of 23 high myopes over minus 10 diopters underwent clear lens extraction and had minimum follow up of 3 months. The preoperative and postoperative refractive status and subjective satisfaction about surgical result were evaluated. The average follow up period was 10.4 months. (range, 3~24 months) RESULTS: Preoperative mean spherical equivalent and mean target refractive error were -17.40+/-4.00D (range, -11.25~-28.25D) and -1.40+/-0.46D (range, -0.3~-2.2D), respectively. Three months postoperatively, mean spherical equivalent was -1.64+/-0.96D (range, +0.5~-3.62 D). Three months postoperatively uncorrected visual acuity was compared with preoperative best spectacle corrected visual acuity. Visual acuity was decreased two lines or more in 4 eyes (10.3%) and in 23 eyes (59.9%) 20/20 was noted or visual acuity increased 2 lines or more. Posterior capsular opacification (PCO) was noted in 12 eyes (30.8 %) and was the most common postoperative complication within 3 months. Three months postoperatively, every patient was asked about their satisfaction of surgery. All except one patient were satisfied with their daily activities after surgery. and all patients except two complained of difficulty in near vision. CONCLUSIONS: The clear lens extraction can improve quality of life in extremely high myopes, but posterior capsular opacity and decreased near visual acuity should be considered in deciding surgery.

Clinical Trial for Visual Rehabilitation with Head Mounted Visual Enhancement System

PURPOSE: To evaluate the clinical effect of Head Mounted Visual Enhancement System. METHODS: We assesd the clinical effect after prescription in 21 patients that visited the low vision clinic from October 2001 to April 2002. RESULTS: The average age is 33.6 years old. The causes of low vison were optic atrophy (29%), retinitis pigmentosa (19%), congenital cataract (14%), macular degeneration (14%). The most common best corrected distant visual acuity before prescription is from 20/200 to 20/100 (42%). After prescription, the most common best corrected distant visual acuity is better than 20/25 (71%). The most common best corrected near visual acuity before prescription is from 20/200 to 20/100 (42%). After prescription, the most common best corrected distant visual acuity is better than 20/25 (81%). The most common purpose to use low vison aids was book reading (57%). CONCLUSIONS: These results show that a application of New Head Mounted Visual Enhancement System will be a great help to increasing low vision populations for visual rehabilitation.

The Comparison of Corneal Ablation Amount by MEL-60 Excimer Laser and Schwind Multiscan Excimer Laser Systems

PURPOSE: The expected corneal ablation amount was compared to the achieved corneal ablation amount in two different excimer laser systems. METHODS: One hundred twenty eyes were recieved Laser In Situ Keratomileusis (LASIK) for the correction of myopia. LASIK was performed with MEL-60 excimer laser and Schwind Multiscan excimer laser system. The central corneal thickness was measured preoperatively, 1 week and 1 month postoperatively by using ultrasonic pachymetry. RESULTS: In eyes with MEL-60 excimer laser, the average expected corneal ablation amount was 81+/-26micro meter and average achieved corneal ablation amount at postoperative one week was 65+/-26 micro meter. There was statistical difference between expected and achieved ablation amount. (p<0.001, paired samples test) In eyes with Schwind Multiscan excimer laser, the average expected corneal ablation amount was 69+/-25 micro meter and average achieved corneal ablation amount at postoperative one week was 69+/-25 micro meter. There was no statistical difference between expected and achieved ablation amount (p=0.761, paired samples test). CONCLUSIONS: The pachymetry at postoperative one week appears to be an useful method to measure the real corneal ablation amount by LASIK with various excimer lasers. Residual stromal bed thickness after LASIK can be presumed, and it helps to decide modality of retreatment.