Clinical Outcomes of an Optimized Prolate Ablation Procedure for Correcting Residual Refractive Errors Following Laser Surgery

PURPOSE: The purpose of this study was to investigate the clinical efficacy of an optimized prolate ablation procedure for correcting residual refractive errors following laser surgery. METHODS: We analyzed 24 eyes of 15 patients who underwent an optimized prolate ablation procedure for the correction of residual refractive errors following laser in situ keratomileusis, laser-assisted subepithelial keratectomy, or photorefractive keratectomy surgeries. Preoperative ophthalmic examinations were performed, and uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction values (sphere, cylinder, and spherical equivalent), point spread function, modulation transfer function, corneal asphericity (Q value), ocular aberrations, and corneal haze measurements were obtained postoperatively at 1, 3, and 6 months. RESULTS: Uncorrected distance visual acuity improved and refractive errors decreased significantly at 1, 3, and 6 months postoperatively. Total coma aberration increased at 3 and 6 months postoperatively, while changes in all other aberrations were not statistically significant. Similarly, no significant changes in point spread function were detected, but modulation transfer function increased significantly at the postoperative time points measured. CONCLUSIONS: The optimized prolate ablation procedure was effective in terms of improving visual acuity and objective visual performance for the correction of persistent refractive errors following laser surgery.

The Change of Corneal Sensitivity and Recovery of Corneal Nerve after Cataract Surgery

PURPOSE: To compare corneal sensitivity and recovery of corneal innervations after a temporal clear corneal incision in cataract surgery. METHODS: We measured changes to corneal sensitivity using Cochet-Bonnet esthesiometer in 25 eyes of 20 patients and analyzed corneal nerve density with confocal microscopy in 20 eyes of 20 patients who had undergone cataract surgery. The parameters were measured before, and at 1 week, 1 month, and 3 months after cataract surgery. RESULTS: The mean preoperative corneal sensitivity was 56.40+/-3.39 mm at the temporal corneal incision site, and there was a significantly decreased sensitivity of 29.80+/-2.69 mm and 42.40+/-4.36 mm postoperatively at 1 week and 1 month, respectively. Nonetheless, by three months, corneal sensitivity had returned to 56.00+/-2.89 mm and was not significantly different from measurements prior to the cataract surgery. The mean preoperative subbasal nerve density was 5296+/-1642 micrometer/mm2. After cataract surgery, the subbasal nerve density was significantly reduced to 4113+/-1421, 3555+/-1448, 4198+/-1239 micrometer/mm2 at 1 week, 1 month, and 3 months, respectively. CONCLUSIONS: Corneal sensitivity after cataract surgery returned to near preoperative levels within 3 months before complete restoration of normal corneal innervations. Therefore, regeneration of subbasal nerve fibers (, as determined by confocal microscopy,) requires more time than the return of corneal sensation after cataract surgery.

The Change of Corneal Sensitivity and Recovery of Corneal Nerve after Cataract Surgery

PURPOSE: To compare corneal sensitivity and recovery of corneal innervations after a temporal clear corneal incision in cataract surgery. METHODS: We measured changes to corneal sensitivity using Cochet-Bonnet esthesiometer in 25 eyes of 20 patients and analyzed corneal nerve density with confocal microscopy in 20 eyes of 20 patients who had undergone cataract surgery. The parameters were measured before, and at 1 week, 1 month, and 3 months after cataract surgery. RESULTS: The mean preoperative corneal sensitivity was 56.40+/-3.39 mm at the temporal corneal incision site, and there was a significantly decreased sensitivity of 29.80+/-2.69 mm and 42.40+/-4.36 mm postoperatively at 1 week and 1 month, respectively. Nonetheless, by three months, corneal sensitivity had returned to 56.00+/-2.89 mm and was not significantly different from measurements prior to the cataract surgery. The mean preoperative subbasal nerve density was 5296+/-1642 micrometer/mm2. After cataract surgery, the subbasal nerve density was significantly reduced to 4113+/-1421, 3555+/-1448, 4198+/-1239 micrometer/mm2 at 1 week, 1 month, and 3 months, respectively. CONCLUSIONS: Corneal sensitivity after cataract surgery returned to near preoperative levels within 3 months before complete restoration of normal corneal innervations. Therefore, regeneration of subbasal nerve fibers (, as determined by confocal microscopy,) requires more time than the return of corneal sensation after cataract surgery.

Prevalence Estimation of Cataract based on a Screening Test

PURPOSE: To estimate the prevalence of cataracts based on screening test results and statistical estimation methods. METHODS: Between June 1994 and September 2005, 85,505 persons aged 20 years and older were screened at a health promotion center for a general health care screen. We assumed that all subjects had complete screening results; however some subjects had an unknown disease status. A 2x3 table form could be generated from this data set. To estimate cataract prevalence, we used a maximum likelihood estimation method to reconstruct a 2x2 table including probabilities for each cell. RESULTS: The overall estimated cataract prevalence was 13.98% (95% confidence intervals, 13.75% to 14.21%). We estimated the prevalence of cataracts to be 15.29% in men (95% confidence intervals, 14.95% to 15.63%) and 12.97% in women (95% confidence intervals, 12.65% to 13.29%). In addition, we found that the cataract prevalence distinctly increased in people aged 60 years or older. CONCLUSIONS: We found that these estimated cataract prevalences were not considerably different from study results obtained in other countries. Therefore, our method may be considered to be appropriate for estimating prevalence. Our results indicate that cataract prevalence in our study population increases with age and highlight the need for early detection and early interventions.

Nerve Growth Factor Concentration and Implications in Photorefractive Keratectomy Versus Laser in Situ Keratomileusis

PURPOSE: To determine whether tear nerve growth factor (NGF) concentration correlates with corneal sensation and ocular surface dryness after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). METHODS: A prospective, non-randomized comparative clinical trial. Seventy eyes of 35 patients and 76 eyes of 38 patients underwent PRK and LASIK procedures to correct myopia and myopic astigmatism, respectively. Total tear protein level, tear NGF concentration, corneal sensation, tear film break-up time (BUT) and Schirmer values were measured before and 1 day, 1 week, 1 month, 3 months, and 6 months after the surgery. RESULTS: The postoperative mean tear NGF/total tear protein ratio (NGF/tP) increased in both PRK and LASIK patients compared to their preoperative levels (p<0.0001). At 1 week and 1 month postoperatively, the NGF/tP ratio was higher in PRK than in LASIK subjects (p<0.0001). Up to 6 months postoperatively, the mean corneal sensation after LASIK in the ablated zone was lower than the preoperative sensation (p<0.0001), whereas this was not the case in PRK subjects. Mean BUT and Schirmer values were significantly lower in LASIK-treated eyes compared to PRK-treated eyes up to 6 months postoperatively (p<0.0001). The early postoperative tear NGF/tP ratio correlated with the postoperative 6 month corneal sensation, BUT and Schirmer values. CONCLUSIONS: The difference in postoperative corneal sensation and ocular surface dryness between PRK- and LASIK-treated eyes was related to the difference in the early postoperative levels of NGF/tP, which implies NGF might influence corneal nerve regeneration after these two surgeries.

Accumulation and Aberrant Modifications of alpha-Crystallins in Anterior Polar Cataracts

Crystallins are the major proteins found in the lens, and the localization of specific crystallins is well known. Overexpression and accumulation of alphaB-crystallin has been observed in response to stress conditions or in certain diseases, such as brain tumors and neurodegenerative diseases. The purpose of this study was to examine whether alpha-crystallins are modified during pathological myofibroblastic changes in lens epithelial cells. Lens epithelial cells attached to the anterior capsules of patients with nuclear or anterior polar cataracts were analyzed quantitatively for alpha-crystallin proteins and mRNAs using Western blot and RT-PCR analysis., respectively. The degree of modification of alpha-crystallins was determined by 2-dimensional gel electrophoresis followed by Western blotting. Higher molecular weight protein bands that were immunoreactive to anti-alphaA- and anti-alphaB-crystallin antibodies around 45 kDa accumulated more in the anterior polar cataract samples than in those with the nuclear type of cataracts. Also monomeric alphaB-crystallins accumulated more in lens epithelial cells of patients with anterior polar cataracts. By comparison, no significant changes were found in the levels of the mRNAs encoding alphaA- and alphaB-crystallins in the different types of cataracts. Both alphaA- and alphaB-crystallin proteins seemed to undergo more extensive modification in anterior polar cataracts. Conclusion. In addition to fibrotic changes, which accompany increased levels of extracellular matrix molecules, accumulation and abnormal modification of alpha-crystallins might be implicated in the pathogenic mechanism of this type of cataract.

The Role of Nuclear Factor Kappa B on Lens Epithelial Cells after Ultraviolet B Irradiation

PURPOSE: This study was performed to determine the role of nuclear factor kappa B (NF-kappa B) on the lens epithelial cell death after ultraviolet (UV) irradiation. METHODS: Simian virus 40 transfected human lens epithelial cells (HLE B-3 cells) were used in this study. UVB located at 10cm from the bottom was irradiated during 1, 2, 3 and 4 minutes. To measure the cytotoxicity MTT assay was used. Translocation of NF-kappa B was examined by immunocytochemistry with anti NF-kappa B p65 antibody and electrophoretic mobility shift assay (EMSA). To confirm the role of NF-kappa B, the cells were pretreated with sulfasalazine, a specific inhibitor of NF-kappa B, for 30 minutes before irradiation, and cytotoxicity and translocation of NF-kappa B were evaluated. RESULTS: UV irradiation produced a progressive cytotoxic effect in cultured HLE B-3 cells after 1 minute and maximum cytotoxicity was reached after 3 minutes irradiation. When HLE B-3 cells were irradiated with UVB, the translocation of NF-kappa B was observed in immunocytochemistry. These translocations were peaked 6 hours after UV irradiation in EMSA. In HLE B-3 cells pretreated with sulfasalazine, the translocation of NF-kappa B was blocked. The cellular death after UV irradiation was markedly blocked by sulfasalazine. UV irradiation can translocate NF-kappa B and sulfasalazine is a useful blocking agent in this pathway. In addition, sulfasalazine can prevent cellular death after UV irradiation. CONCLUSIONS: These findings suggest that NF-kappa B plays an important role in cellular death after UV irradiation.

The Effect of Larger and Blend Zone Ablation on Optical Aberrations in Laser Epithelial Keratomileusis (LASEK)

PURPOSE: The purpose of this study is to investigate the postoperative high order aberration after LASEK and to evaluate the effects of LASEK on high order aberration using larger and blend zone ablation. METHODS: Twenty patients out of 28 patients who received treatment were followed up for 3 months. In each case, one eye received conventional ablation LASEK and the other eye received larger and blend zone ablation LASEK. Preoperative and postoperative RMS (root mean square) of Bille aberration maps measurements were made with WaveScan Wavefront(TM) system (VISX, Santa Clara, U.S.A.). RESULTS: RMS of Bille aberration maps at post operation 1 month and post operation 3 months displayed a statistically significant increase compared with preoperative value. (p<0.05) In post operation 3 month, larger and blend zone ablation LASEK treated eyes displayed a statistically significant lower post operative RMS compared to those of conventional ablation LASEK.(p<0.05) CONCLUSIONS: High order aberrations at post operation 1 month and post operation 3 months increased compared with preoperative value. High order aberration after LASEK with larger and blend zone ablation are less pronounced compared to those associated with conventional ablation LASEK. By using larger and blend zone ablation it is possible to minimize the high order aberration of the eye and improve visual results for patients undergoing LASEK.

Necrotizing Conjunctival Ulceration following Subconjunctival Atropine Depot Injection

PURPOSE: To report a case of severe conjunctival necrosis associated with scleral melting following subconjunctival atropine depot injection in treating posterior synechiae associated with uveitis. METHODS: A 31-year-old male patient visited our clinic after subconjunctival injection of 1% atropine, 0.4 ml, in treating circular posterior synechiae associated with uveitis in his left eye. The marked conjunctival injection and chemosis around the limbus were noted. Three days after first visit to our clinic, remarkable necrosis had developed around the whole limbus, and newly developed whitish necrotic tissue was noted over sclera and episclera. We debrided the necrotic conjunctiva and episclera, and the exposed sclera was grafted with amniotic membrane. REUSLTS: After 4 weeks, the complete re-epithelization of necrotized defect was shown and there were no evidence of inflammation, symblepharon, or scleral melting. CONCLUSIONS: In usage of atropine, especially to eyes locally, subconjunctival injection should be avoided due to direct toxicity to the conjunctiva and sclera to form necrosis and melting. The damaged lesions of conjunctiva and sclera due to usage of this drug generally cause chronic inflammation and persistent surface defect. In order to restore and re-epithelize the necrotic defect, more aggressive treatment such as an amniotic membrane transplantation would be needed.