Effect of the Aspheric RGP Lens on Corneal Topography and Endothelial Cell in Keratoconus

PURPOSE: To analyze the effects of the aspheric rigid gas permeable (RGP) lens on the corneal topography and endothelial cells in eyes with keratoconus. METHODS: Sixty five eyes of 35 keratoconic patients who had follow-up of more than 6 months were included in the study. Thirty eyes of 16 patients wore aspheric RGP lens, and the remaining control eyes did not wear any lens. After aspheric RGP lens fitting, visual acuity and manifest refractive error were evaluated, Slit lamp examination and corneal topography were also done. Mean cell area and density of corneal endothelial cell were measured by specular microscopy at first visit and 6 months after lens fitting. RESULTS: After lens fitting, the percentage of best corrected visual acuity of better than 20/25 was 93.3% (28 eyes). The change of astigmatism, the Steepest Simulated keratometry reading, Surface asymmetry index, Surface regularity index, and apical corneal power were significantly increased in the keratoconic cornea in aspheric lens fitting group compared to the control group (p0.05). CONCLUSIONS: Short-term wearing of aspheric RGP lens in keratoconic patients showed no effect on corneal endothelial cells. However, it increased the irregularity and steepening of the keratoconic cornea. It may indicate that mid-peripheral corneal-to-lens relationship may be inappropriate when keratoconus is fitted with aspheric lens.

The Effect of RGP Lens and Reverse Geometry Lens on Corneal Epithelial Proliferation Rate in Rabbit

PURPOSE: To investigate proliferation rate of the corneal epithelium with rigid gas permeable lens(RGP) or reverse geometry lens(RGL) wearing. METHODS: Twenty-four rabbits were fitted with either a RGP or RGL on right eye, with left eye serving as a control. They were sacrificed at 1, 3, 7, and 14 days after lens fitting. after immunohistochemistry using 5-bromo-2-deotyuridine, BrdU-labeled cells were counted in 10-medium power fields (X200) in each sample using light microscope by 1.0 mm intervals between superior limbus and the center. RESULTS: The number of BrdU-labeled cells was highest in peripheral cornea, and lowest in limbus(p<0.05). The BrdU-labeled cells of limbus increased by 127% but labeled-cells of the center decreased by 24% in RGP group after 1-day fitting. Increase of the labeled cells was observed in the mid-peripheral and central cornea by 12% and 121% each but the decrease of labelled cells was found at the limbus by 16% in RGL fitting group at 1 day. After 14days, Both RGP and RGL group showed decrease of BrdU-labeled cells in limbus by 8% each, and in the center by 32% and 63%, respectively. CONCLUSIONS: Normal rabbit cornea was characterized by different epithelial proliferation rates according to location. However these pattern was significantly altered with both RGL and RGP fitting group. The change was greater in RGL group than in RGP group. This suggested wearing the RGL might be less physiologic than RGP fitting.

Effect of Both Lateral Rectus Resection for Residual Esotropia

PURPOSE: To investigate the surgical outcome of both lateral rectus resection in the treatment of residual esotropia with previous both medial rectus recession METHODS: The medical record of 30 patients who had underwent both lateral rectus resection from 1996 to 2001 for residual esotropia occurred after bilateral medial rectus recession and who had followed up for more than one year, were analysed retrospectively. Successful outcome was defined as esotropia 0.05), but it was not significant statistically. Postoperative angle of deviation in group II was increased from 8.1+/-4.6PD at postoperative 1 day to 13.8+/-7.9PD at postoperative 1 year (p<0.001). CONCLUSIONS: Both lateral rectus resection is an effective method in the treatment of residual esotropia less than 40 PD.

Effect of Reverse Geometry Lens on Correction of Moderate-degree Myopia and Cornea

PURPOSE: To evaluate the effect of reverse geometry lens (RGL) on correction of moderate degree myopia and cornea in patients of moderate-degree myopia. METHODS: 48 eyes of 82 eyes were chosen to wear reverse geometry lens and the remaining 34 eyes were fitted with rigid gas permeable (RGP) lens. The subjects were tested three days, one, two weeks, one, two and three months after fitting the lens. Uncorrected visual acuity, manifested refractive error, corneal thickness and corneal endothelial cell count were evaluated. corneal topography were performed. RESULTS: The uncorrected visual acuity was increased at 0.05 LogMAR after two weeks. and manifested refractive error decreased during the first months, thereafter stabilizing to -0.2 D (diopters). Corneal thickness was 540.4 micrometer and 583.0 micrometer in the center and mid-periphery, decreased to 505.2 micrometer and 572.7 micrometer, respectively, three months after RGL fitting (p<0.05). Endothelial cell count was 2663.5 cells/mm2 and 2541.5 cells/mm2 in the center and mid-periphery, 3 months after RGL fitting and endothelial cell count was not significantly different compared with that of pre-fitting. There was no statistical difference between RGL fitting group and RGP fitting group in the change of corneal endothelial cell count. CONCLUSIONS: RGL was found to be effective in correction of moderate-degree myopia. It had minimal effect on corneal endothelium, in short-term usage, however, the change of corneal thickness suggests that RGL fitting may effect on corneal epithelium and stroma.

Effect of Both Medial Rectus Recession in Large Angle Infantile Esotropia

PURPOSE: To evaluate of the effect of bilateral medial rectus recession in the patients who showed large angle (>50 prism diopters, PD) infantile esotropia as comparing small angle (50 PD, 14 patients) and small angle group (

The Effects of Placement of Silicone Tube and e-PTFE Stent in External Dacryocystorhinostomy

PURPOSE: To determine the surgical results of bicanalicular silicone tube and e-PTFE (expanded polytetrafluoroethylene) stent in external dacryocystorhinostomy without flap. METHODS: Sixteen patients had been placed with bicanalicular silicone tube and e-PTFE stent and 17 patients with silicone tube only in external dacryocystorhinostomy without flap. We examined the presence of epiphora symptom, passage of dye, and inflammatory change or granuloma formation of nasal mucosa at postoperative 1 day, 1 week, 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 24 weeks. RESULTS: Success rate was higher in double stent group (81.3%) than that in control group (76.5%). But there was no statistically significant (difference between two groups. p=0.085). At nasal endoscopic examination, one case (6.3%) of granuloma was noted in double stent group, and two cases (11.8%) in control group. Membraneous obstruction was not observed in double stent group but one case (5.9%) in control group. CONCLUSIONS: In case of structural deteriolation of midface including nasolacrimal duct, placement of bicanalicular silicone tube with e-PTFE stent may be an useful method in external dacryocystorhinostomy without flap.

Comparison of Frontalis Sling and Levator Resection for Recurrence after Frontalis Sling in Congenital Ptosis

PURPOSE: To compare the success rate of two procedures frontalis sling operation and maximal levator resection for recurred congenital ptosis. METHODS: In the 44 eyes in 30 patients who had recurrence after frontalis sling using banked fascia lata, 21 eyes received frontalis sling operation using autogenous fascia lata (Group I), and the other 23 eyes received maximal levator resection with aponeurotic approach (Group II). Follow up was made at one month, three months, six months and one year after the operation. RESULTS: Six months after the operation, Group I showed 81.0% while Group II showed 78.3% in success rate. One year after the operation, Group I had 76.2%, while Group II had 73.9% in success rate. There were no significant statistical difference between the two groups (p=0.744, 0.707). CONCLUSIONS: In cases of recurrence after frontalis sling using banked fascia lata in treating congenital ptosis patients, we found the frontalis sling using autogenous fascia lata to be effective. The maximal levator resection may be used as an alternative procedure.

Effect of Both Lateral Rectus Recession in Large Angle Exotropia

PURPOSE: To evaluate of the effect of both lateral rectus recession according to the amount of the recession in the patients who showed large angle (>or=35 prism diopter, PD) exotropia. METHODS: The 120 patients who underwent both lateral rectus recession and followed up more than 1 year between 1996 to 2002 at Chung-nam university hospital, were reviewed. The effect of both lateral rectus recession was compared according to the amount of recession and preoperative angle of deviation. Successful outcome was defined as esotropia

The Effect of RGP Lens and Reverse Geometry Lens on Apoptosis in Rabbit Cornea

PURPOSE: To investigate the cytotoxic effect of rigid gas permeable(RGP) and reverse geometry lens(RGL) on rabbit corneal cells. METHODS: In 36 white rabbits, right eyes were worn with either RGP or RGL. Left eyes were served as control. The rabbits were sacrificed at 1, 3, 7, 14 days after fitting and 7, 14 days after removal. Morphological changes of the basal epithelial cells and stromal keratocytes were observed using the light and transmission electron microscopy. The samples were examined after TUNEL staining in 3 high power fields (x400). RESULTS: In control eyes, 2.26% of central corneal epithelial cells showed apoptosis. After RGP wearing, the epithelial apoptosis decreased by 0.32% compared to control eyes(2.17%) at 14 days(p<0.001), and returned to 1.55% at 14 days after lens removal(2.04% in control, p=0.161). After RGL wearing, the degree of apoptosis was also lower than control(3.22%) by 0.30% at 14 days(p=0.003). However, it increased to 0.75% at 14 days after lens removal(1.67% in control, p=0.077). A few TUNEL positive fibroblasts were found in superficial stroma in both RGP and RGL group, but not in control eyes. CONCLUSIONS: Both RGP and RGL wearing may decrease the degree of apoptosis in corneal epithelium and lead the apoptosis in corneal stroma. The degree of apoptosis was recovered after lens removal, suggesting the process might to be reversible. The fitting with RGL induced apoptosis of keratocyte more than the fitting with RGP did. It suggests that the RGL wearing may be less physiologic than RGP wearing.

Intraocular Pressure Change after Glaucoma Implant Surgery with Releasable suture

PURPOSE: To find the factor that affects the long-term intraocular pressure after glaucoma implant surgery with releasable suture. METHODS: We retrospectively reviewed the medical records of the 33 patients (36 eyes) who had undergone glaucoma implant surgery with our own expanded-Polytetrafluoroethylene (e-PTFE) membrane-tube implant with temporary closure of the tube by releasable suture. Data such as timing of suture release, IOP's before and after surgery and the amount of pressure change during follow-up were collected, and we tried to find the factor that influenced the IOP at the last visit. RESULTS: The preoperative IOP was 43.2+/-14.6 mmHg and the suture was released at day 17.9+/-9.5 after surgery. The IOP just before the release of suture was 33.5+/-17.1 mmHg. The pressure was dropped to 15.1+/-13.7 mmHg, measured at 30 minutes after the release of the suture. The IOP was stabilized to 14.9 +/-9.5 mmHg at 12.2+/-7.0 days after the release. The average follow-up was 32.8+/-26.3 months and the IOP at the last visit was 17.3+/-10.5 mmHg. Four eyes (11%) had hypotony (IOP less than 8 mmHg) before release of the suture, thirteen eyes (41%) showed hypotony 30minutes after release, and three eyes(8%) showed hypotony at the last visit. Multiple linear regression analysis revealed that the IOP at 30 minutes after release of the suture had a positive correlation with the IOP at the last visit (r=0.642,p=0.000). CONCLUSIONS: In the membrane-tube implant surgery for the refractory glaucoma, the releasable suture echnique is helpful to prevent the early postoperative hypotony. By measuring early post-release IOP after implant surgery with releasable suture technique, we might predict the behavior of long term IOP change; the lower post-release IOP, the better long-term pressure control.

Effect of Unilateral Lateral Rectus Recession for Intermittent Exotropia under 25 PD

PURPOSE: To investigate the surgical outcome of unilateral lateral rectus recesssion in the treatment of intermittent exotropia under 25 prism diopter (PD). METHODS: The 62 patients who had underwent unilateral lateral rectus recession and followed up for 6 months or larger, were reviewed. Following inferotemporal fornix incision, 8.5 mm or 9.5 mm recession from the insertion of lateral rectus was performed in 20 PD or in 25 PD intermittent exotropia respectively. RESULTS: Mean age of patients was 8.8 years (5-14 years) and follow up time was 11.5 months (6-34 months) on average. Postoperative deviation and success rate were as followings: -0.2+/-2.1 PD, 91.9% at postoperative 1 day, 0.5+/-2.3 PD, 95.2% at postoperative 1 week, 2.5+/-3.9 PD, 96.8% at postoperative 1 month, 3.7+/-5.0 PD, 91.9% at postoperative 6 month and 4.3+/-5.5 PD, 85.7% at postoperative 1 year. The average divergent shift was 4.5 PD during whole examination period and this shift showed significant change during same period (Repeated measures, p=0.000). The occurrence rate of undercorrection was 1.6% at postoperative 1 week, 3.2% at postoperative 1 month, 8.1% at postoperative 6 month and 14.3% at postoperative 1 year. The occurrence rate of overcorrection was 8.1% at postoperative 1 day and 3.2% at postoperative 1 week. All cases of overcorrection were orthophoric after postoperative 1 month. The limitation of abduction was not discovered in all cases at postoperative 1 year. CONCLUSIONS: Unilateral recession of lateral rectus is an effective method in the treatment of intermittent exotropia under 25 PD. However long term follow up should be considered since undercorrection seems to be increasing.