Diferentes concentraciones de mitomicina C en la prevención del haze en la queratectomía fotorrefractiva / Different concentrations of mitomycin C for haze prevention in photorefractive keratectomy

Objetivo: Evaluar la utilidad de dos concentraciones de mitomicina C para la prevención del haze en la queratectomía fotorrefractiva. Métodos: Se realizó un estudio experimental aleatorizado en 26 ojos de 17 pacientes con defectos miópicos. Los pacientes fueron asignados a dos grupos según las dosis de mitomicina C (0,02 por ciento grupo 1 y 0,002 por ciento grupo 2). La variable de respuesta principal fue la presencia de haze. Se buscó correlación entre la magnitud del haze con grado de ametropía tratada, profundidad de ablación, microscopia endotelial y resultados visuales y refractivos. Resultados: A los 6 meses la mayoría de los pacientes del grupo 1 no presentó haze (ocho ojos / 57 por ciento), y del grupo 2 mantuvieron haze 0,5 (6 ojos / 50 por ciento). En la ametropía severa el haze en el grupo 2 fue mayor que en el grupo 1 durante todo el posoperatorio, y se observó la mayor diferencia al sexto mes con 0,5 ± 0,4 vs. 1,5 ± 0,32. En ablaciones > 75 micras el grupo dos terminó con más haze que el uno, con 0,5 ± 0,44 vs. 1,75 ± 0,76. La agudeza visual sin corrección se vio más afectada en el grupo 2. No hubo daño endotelial en ningún grupo. Conclusión: La presencia de haze predomina en los casos tratados con dosis 0,002 por ciento de mitomicina C, comparada con la dosis 0,02 por ciento, aunque en este caso ambos grupos mantuvieron un resultado visual y refractivo adecuado y baja toxicidad endotelial.

Objective: Evaluate the usefulness of two concentrations of mitomycin C for haze prevention in photorefractive keratectomy. Methods: An experimental randomized study was conducted of 26 eyes of 17 patients with myopic defects. The patients were divided into two groups according to their mitomycin C doses (Group 1: 0.02 percent and Group 2: 0.002 percent). The main response variable was the presence of haze. Verification was performed of the correlation between haze magnitude and the degree of the ametropia treated, ablation depth, endothelial microscopy, and visual and refractive results. Results: At six months most patients in Group 1 did not have any haze (eight eyes / 57 percent), whereas 0.5 (6 eyes / 50 percent) in Group 2 still had haze. In severe ametropia, haze was larger in Group 2 than in Group 1 throughout the postoperative period, the greatest difference being observed in the sixth month with 0.5 ± 0.4 vs 1.5 ± 0.32. In ablations > 75 microns, Group 2 ended with more haze than Group 1, with 0.5 ± 0.44 vs 1.75 ± 0.76. Uncorrected visual acuity was more affected in Group 2. No endothelial damage occurred in either group. Conclusion: The presence of haze prevails in cases treated with 0.002 percent doses of mitomycin C, as compared with 0.02 percent doses, though in this case both groups maintained an appropriate visual and refractive result and low endothelial toxicity(AU)

Quantitative analysis of residual ethanol content in corneal epithelium flaps in LASEK / 眼科新进展

Objective To detect and analyze of residual ethanol in abandoned flaps after laser subepithelial keratomileusis (LASEK) with ethanol infiltration methods.Methods Together 20 patients (40 eyes) undergoing LASEK were recruited in the study.After infiltrated with 20％ ethanol and rinsed in equilibration solution,the corneal epithelial free flap was isolated and removed in time for sealing,and then procedures were continuously completed.Finally,observation of the skin flap production,postoperative irritation symptoms,epithelial healing,visual recovery and postoperative haze situation was performed,and then the amount of ethanol in the epithelial flap was measured.Results There was no failure in making the intact corneal flaps.The sensory score of postoperative irritation was 2.52 ± 1.46.Neonatal epithelial with 1 grade was observed in 32 eyes,2 grade in 8 eyes 5 days after surgery,while corneal haze with 0.5 grade was occurred in 3 eyes,1 grade in 2 eyes 12 weeks after surgery.There were ethanol residues in corneal epithelium in the abandoned flaps,with the amount of ethanol residues of (0.205 2 ± 0.041 0) μL in each flap.Conclusion It is found that a certain amount of ethanol residue in the corneal epithelium after LASEK with ethanol infiltration equilibration solution rinse,which may be one reason of the corneal irritation symptoms and corneal haze.

Study on the mechanism of amniotic extraction inhibiting haze formation after Epi-LASIK in rabbit cornea / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the probably mechanism of amniotic extraction inhibiting haze formation after epipolis laser in situ keratomileusis (Epi-LASIK) in rabbit cornea.METHODS: Thirty rabbit corneas were performed with Epi-LASIK.All eyes were randomly divided into three groups: eyes treated with amniotic extraction (AE group),eyes treated with 1g/L dexamethasone (hormone group) and eyes treated with solvent (solvent control group).Haze grade evaluation was performed under the slit lamp after Epi-LASIK for 1,4 and 8wk.The repair of corneal epithelium was observed by using HE staining,and the expression of NF-kB protein P65 was detected by immunohistochemistry.The expression levels of inflammatory cytokines (TNF-α,TGF-β1 and IL-1) and anti-inflammatory cytokines (IL-4,IL-10 and IL-13) were determined by ELISA.RESULTS: HE staining showed that the basal cells of corneal epithelium were more uniform and arranged regularly in AE groups after Epi-LASIK for 1wk as compared with the hormone group and the solvent control group.After 4wk,there were a few of new collagen fibers in the superficial stroma of AE group,forming a small amount of scar.After 8wk,the corneal stroma of AE group showed a small amount of new collagen fibers,arranged regularly,and rarely formed scar.At the early stage (1 and 4wk),AE treatment has an obviously effect on inhibiting the secretion of inflammatory factors (TNF-α,TGF-β1 and IL-1) and anti-inflammatory factors (IL-4,IL-10 and IL-13),and the difference was statistically significant (P<0.01).Moreover,the activation of the NF-kB signaling pathway was significantly inhibited by treatment with AE in the early postoperative period (1 and 4wk).CONCLUSION: Amniotic extraction may reduce the inflammatory response in corneal epithelial cells by inhibiting the NF-kB signaling pathway,thereby inhibiting the formation of collagen and scar and the occurrence of haze.

Corneal melanosis successfully treated using topical mitomycin-C and alcohol corneal epitheliectomy: a 3-year follow-up case report / Tratamento com êxito da melanose de córnea utilizando mitomicina-C tópica e epiteliectomia auxiliada por álcool: relato de caso com três anos de seguimento

ABSTRACTWe report a case of primary acquired corneal melanosis without atypia associated with corneal haze in a patient with a history of limbal malignant melanoma and the effect of mitomycin-C. A 75-year-old woman with a history of limbal malignant melanoma presented with loss of vision in right eye. Corneal examination showed a patchy melanotic pigmentation with a central haze. Topical mitomycin-C improved visual acuity and corneal haze. However, the pigmented lesions persisted, and they were removed with alcohol corneal epitheliectomy. Histopathological examination demonstrated primary acquired melanosis without atypia. The lesions were successfully removed, and there were no recurrences during the follow-up period of 36 months. The association of conjunctival and corneal melanosis without atypia is a rare condition. In addition, co-existence of central corneal haze and melanosis may decrease visual acuity. Topical mitomycin-C and alcohol corneal epitheliectomy can be useful treatments in this condition.

RESUMORelatar um caso de melanose adquirida primária de córnea sem atipia, associado a haze corneano em um paciente com história de melanoma maligno de limbo e o efeito da mitomicina-C. Uma mulher de 75 anos de idade, com história de melanoma maligno do limbo apresentado com diminuição de visão no olho direito. O exame de córnea mostrou uma pigmentação melânica irregular com um haze central. O uso de mitomicina-C tópica levou à melhora da acuidade visual e da opacidade corneana. No entanto, as lesões pigmentadas persistiram e foram removidas com epiteliectomia associada ao álcool. O exame histopatológico demonstrou melanose adquirida primária sem atipia. As lesões foram removidas com êxito, e não houve recidiva durante o período de acompanhamento de 36 meses. A associação melanose sem atipia da conjuntiva e da córnea é uma condição rara. Além disso, a coexistência de haze corneano central e melanose pode diminuir a acuidade visual. O uso de mitomicina-C tópica e epiteliectomia corneana auxiliada pelo álcool podem ser tratamentos úteis nessa situação.

Air assisted lamellar keratectomy for the corneal haze model

To standardize the corneal haze model in the resection depth and size for efficient corneal haze development, air assisted lamellar keratectomy was performed. The ex vivo porcine corneas were categorized into four groups depending on the trephined depth: 250 microm (G1), 375 microm (G2), 500 microm (G3) and 750 microm (G4). The stroma was equally ablated at the five measurement sites in all groups. Significant differences were observed between the trephined corneal depths for resection and ablated corneal thickness in G1 (p < 0.001). No significant differences were observed between the trephined corneal depth for resection and the ablated corneal thickness in G2, G3, and G4. The resection percentage was similar in all groups after microscopic imaging of corneal sections. Air assisted lamellar keratectomy (AK) and conventional keratectomy (CK) method were applied to six beagles, after which development of corneal haze was evaluated weekly until postoperative day 28. The occurrence of corneal haze in the AK group was significantly higher than that in the CK group beginning 14 days after surgery. Alpha-smooth muscle actin expression was significantly higher in the AK group (p < 0.001) than the CK group. Air assisted lamellar keratectomy was used to achieve the desired corneal thickness after resection and produce sufficient corneal haze.

Effects of Topical Tranilast on Corneal Haze with the Pentacam(R) after Photorefractive Keratectomy

PURPOSE: To evaluate the inhibitory effect of tranilast on formation of corneal haze using the Pentacam(R) after photorefractive keratectomy (PRK). METHODS: A prospective, randomized, paired eye study was performed. A total of 60 eyes from 30 patients were enrolled in the present study. Eyes were categorized as myopic eyes or =-5 D. Patients undergoing PRK were randomized to receive tranilast in one eye and no medication in the contralateral eye. Three months postoperatively, corneal haze was measured with the Pentacam(R) and compared between the 2 groups. RESULTS: Statistical differences were not found in preoperative data in the tranilast or control groups (all P > 0.05). There was a strong decreasing density trend from the apex to the 3 mm radius in both groups (P 0.05). CONCLUSIONS: The use of tranilast after PRK did not inhibit corneal opacity. Additionally, Pentacam(R) can provide a useful objective measure of corneal haze.

Evaluation of the Prophylactic Use of Mitomycin to Inhibit Haze Formation after LASEK

PURPOSE: To evaluate the effects of the prophylactic use of mitomycin C in low concentration and short duration (0.01%, 60 sec) in inhibiting haze formation after laser epithelial keratomileusis (LASEK). METHODS: Forty-two eyes of 71 patients with refractive error from -5.0 D to -8.50 D were enrolled in this study. The eyes were divided into 2 groups according to the use of mitomycin C. All eyes were examined for refraction, UCVA, BCVA, and the incidence and degree of corneal haze before surgery and at 1, 3, 6 months after operation. RESULTS: Fifty-one eyes were operated by LASEK with intraoperative application of 0.01% mitomycin C for 60 seconds and 20 eyes were operated by LASEK without mitomycin C. There was no statistical difference in UCVA, BCVA, and spherical equivalent between 2 groups. In the study group, the degree of corneal haze was 0.54+/-0.39. 0.38+/-0.48, 0.30+/-0.50 at 1, 3, 6 months after operation and in the control group, 0.92+/-0.58, 0.79+/-0.66, 0.50+/-0.60 at 1, 3, 6 months after operation respectively. The difference in the postoperative corneal haze between 2 groups was statistically significant at 1, 3 months after operation, but at 6 months the difference was not statistically significant. CONCLUSIONS: In this study, intraoperative single use of mitomycin C in lower concentration and short duration could reduce the formation of corneal haze effectively in early postoperative period after LASEK. A more longterm period of follow up will be required to assess the continuous effect of mitomycin C on inhibiting corneal haze after LASEK.

Effect of Mitomycin C to Inhibit Corneal Haze Formation after Photorefractive Keratectomy for High Myopia

PURPOSE: To evaluate the safety and results of the prophylactic use of 0.02% mitomycin C (MMC) to inhibit haze formation after excimer laser photorefractive keratectomy (PRK) for high myopia in eyes that were not good candidates for laser in situ keratomileusis (LASIK) because of inadequate corneal thickness. METHODS: On thirty eyes with high myopia (-6.0 to -10.13 diopters), PRK with intraoperative topical 0.02% MMC application was performed. Visual acuity, refraction, keratometry, corneal haze, central corneal thickness, corneal endothelium, repair of corneal epithelium, and other complications were evaluated for 1 year. RESULTS No eyes showed any BCVA loss, and some even presented a BCVA increase, except in one case: one eye had lost a line 1 year after PRK. At 1 year after surgery, the spherical equivalent was within +/-0.5 D of the desired refraction in 73.33% of the cases, and 86.67% were within +/-1.0 D of the intended refraction. At 3 months after surgery, the mean corneal haze scale stabilized at about 0.22, and decreased further thereafter. Central corneal thickness increased steadily postoperatively, whereas endothelial density decreased significantly, however, the percentage of hexagonal cells and coefficient of variation in cell area showed no change. Epithelial regeneration was complete within 4 days, and there were no other complications. CONCLUSIONS: The prophylactic use of a 0.02% MMC applied intraoperatively after PRK produced lower haze rates and a better visual outcome. But, due to the decrease in endothelial cell density, the safety of MMC can be determined only after long-term observation.

Effect of Mitomycin C to Inhibit Corneal Haze Formation after Photorefractive Keratectomy for High Myopia

PURPOSE: To evaluate the safety and results of the prophylactic use of 0.02% mitomycin C (MMC) to inhibit haze formation after excimer laser photorefractive keratectomy (PRK) for high myopia in eyes that were not good candidates for laser in situ keratomileusis (LASIK) because of inadequate corneal thickness. METHODS: On thirty eyes with high myopia (-6.0 to -10.13 diopters), PRK with intraoperative topical 0.02% MMC application was performed. Visual acuity, refraction, keratometry, corneal haze, central corneal thickness, corneal endothelium, repair of corneal epithelium, and other complications were evaluated for 1 year. RESULTS No eyes showed any BCVA loss, and some even presented a BCVA increase, except in one case: one eye had lost a line 1 year after PRK. At 1 year after surgery, the spherical equivalent was within +/-0.5 D of the desired refraction in 73.33% of the cases, and 86.67% were within +/-1.0 D of the intended refraction. At 3 months after surgery, the mean corneal haze scale stabilized at about 0.22, and decreased further thereafter. Central corneal thickness increased steadily postoperatively, whereas endothelial density decreased significantly, however, the percentage of hexagonal cells and coefficient of variation in cell area showed no change. Epithelial regeneration was complete within 4 days, and there were no other complications. CONCLUSIONS: The prophylactic use of a 0.02% MMC applied intraoperatively after PRK produced lower haze rates and a better visual outcome. But, due to the decrease in endothelial cell density, the safety of MMC can be determined only after long-term observation.

Comparison of Photorefractive Keratectomy and Laser Epithelial Keratomileusis for Low to Moderate Myopia

PURPOSE: To compare the efficacy and safety of photorefractive keratectomy with laser epithelial keratomileusis, for low to moderate myopia. METHODS: Patients with a manifest refraction less than -6.0 diopters were enrolled in this study. Patients were treated with photorefractive keratectomy (47 eyes) or laser epithelial keratomileusis (42 eyes). Preoperative and postoperative uncorrected visual acuity, refractive errors, keratometry, residual central corneal thickness, epithelial healing time, and corneal haze were evaluated for a 1 year follow-up period. RESULTS: There were no significant differences between photorefractive keratectomy and laser epithelial keratomileusis in uncorrected visual acuity, refractive errors or correction of refractive errors. Residual central corneal thickness increased until 6 months postoperative and thereafter in both photorefractive keratectomy and laser epithelial keratomileusis groups. There were no significant changes in keratometry after postoperative 1 month. Epithelial healing time of photorefractive keratectomy was shorter than that of laser epithelial keratomileusis. Corneal haze score had a peak at 1 month postoperative and then decreased rapidly until 3 months postoperative, it was stable after 6 months. Corneal haze score at 1 month was less than 0.5 in both groups and did not disturb visual acuity. CONCLUSIONS: Photorefractive keratectomy and laser epithelial keratomileusis have an equal effect in correction of visual acuity and refractive errors. They have equivalent levels of safety as measured by postoperative residual central corneal thickness and corneal haze. Both procedures are effective methods to correct low to moderate myopia.

Short Term Clinical Results of Laser Epithelial Keratomileusis and Epi-Laser in Situ Keratomileusis for Moderate and High Myopia

PURPOSE: To compare the results of laser epithelial keratomileusis (LASEK) and epi-laser in situ keratomileusis (Epi-LASIK) for the treatment of moderate to high myopia. METHODS: In this study, 50 patients with a manifest refraction of moderate to high myopia were assigned to two groups: 50 eyes of 25 patients treated with LASEK and 50 eyes of 25 patients treated with epi-LASIK. Uncorrected visual acuity (UCVA), manifest refraction, corneal haze, and postoperative pain were reviewed in LASEK and epi-LASIK treated eyes at 3 months after the operation. RESULTS: At one week after surgery, UCVA was recovered more rapidly after epi-LASIK than LASEK (LASEK: 0.61+/-0.23, Epi-LASIK: 0.79+/-0.11, p<0.05), but UCVA at both 1 and 3 months showed no significant difference between the LASEK and epi-LASIK groups. However, epi-LASIK-treated eyes had lower postoperative pain scores and lower corneal haze scores (1 month; p=0.01) than those of LASEK-treated eyes. CONCLUSIONS: Epi-LASIK showed a more rapid visual recovery than LASEK at 1 week after surgery for the correction of myopia. Epi-LASIK-treated eyes also had less postoperative pain and an earlier reduction of postoperative corneal haze. These results suggest epi-LASIK could be a viable alternative procedure for the correction of moderate to high myopia.

Pachymetric Measurements Using Orbscan after Excimer Refractive Surgery

PURPOSE: To assess the accuracy of pachymetric measurement using Orbscan(Bausch and Lomb, USA) after laser in situ keratomileusis(LASIK), photorefractive keratectomy(PRK), and laser epithelial keratomileusis (LASEK). METHODS: Central corneal thickness of 159 nonoperated normal eyes, 55 eyes after LASIK, 12 after PRK, and 17 after LASEK was measured using ultrasound and Orbscan II. The acoustic factor (AF) was adjusted, based on the results obtained in the normal eye group, to minimize the difference between ultrasound and Orbscan pachymetric values. RESULTS: Using the adjusted AF (0.9607), the mean difference between Ultrasonic pachymetric and Orbscan measurement was 0.00 +/- 21.08, 20.44 +/- 24.12, 27.63 +/- 36.87, and 0.56 +/- 17.26 micro meter in the normal, LASIK, PRK, and LASEK groups, respectively. In the LASIK and PRK groups, there was a statistically significant difference between the two methods (both P<0.001). The postoperative ultrasound measurements were consistent with the theoretical residual corneal thickness in the LASIK and PRK groups (-2.96 +/- 18.00 micro meter, -1.00 +/- 13.59 micro meter), while Orbscan measurements were statistically significantly less than the theoretical residual corneal thickness in the LASIK and PRK groups (21.84 +/- 31.06 micro meter, p<0.001; 21.88 +/- 35.91 micro meter, P=0.036). CONCLUSIONS: Orbscan pachymetric values may be underestimated and less accurate after excimer refractive surgery, especially after LASIK and PRK.

Two Year Clinical Results of LASEK (Laser Epithelial Keratomileusis) for Correcting Myopia

PURPOSE: To evaluate efficacy and stability of vision correction and corneal haze of LASEK. METHODS: We reviewed 16 patients (30 eyes) who had undergone LASEK from October 1999 to April 2000. And we divided them into two groups and followed up 2 years (Group I: manifest refraction is from -3.0D to -6.0D, Group II: manifest refraction is from -6.25D to -10.25D). RESULTS: Mean uncorrected visual acuity (by logMAR) is improved from 1.28 +/- 0.40 to 0.02 +/- 0.05 one year after LASEK and reserved 0.02 +/- 0.04 two years after LASEK. Both groups showed over 20/25 of uncorrected visual acuity in one year and also two years after LASEK. Spherical equivalent less than 1.0 diopter in Group I and II was 85.7 % and 75.0 % of eyes one year after LASEK and 92.9 % and 81.3% of eyes two years after LASEK respectively. Myopic regression mostly occurred from 1 week to 2 months and remained stable after 1 year. Serious complications were not observed and corneal haze had no clinical significance. CONCLUSIONS: Efficacy of LASEK in the aspects of myopic correction and visual improvement is good and myopic regression and corneal haze was minimal. So LASEK is a good procedure to correct myopia.

A Case of Steroid Treatment on Haze after LASIK Retreatment in eye with previous PRK

PURPOSE: A corneal haze after LASIK retreatment in eye with previous PRK has not been reported in Korea. We experienced a case of myopic regression and haze after LASIK retreatment and treated it with fortified steroid eye solution. Herein we will present it. METHODS: A 38-year-old woman underwent the PRK for the correction of myopia in 1994 and the bilateral LASIK retreatment of myopic regression in January 2000. One year later, the left eye showed myopic regression and severe corneal haze but right eye was nearly emmetropia. PredForte(R) was dropped 4 times daily for 3 months, tapered, substituted with Flumetholon(R) for the next 3 months. We observed for 6 months. RESULTS: Three months later, refraction became nearly emmetropic and uncorrected visual acuity was 0.6. Corneal haze, central keratometric and pachymetric value were much decreased. It remained stable for 6 months.

Comparison of Laser Epithelial Keratomileusis(LASEK) in One Eye and Photorefractive Keratectomy(PRK) in Other Eye for Low to Moderate Myopia

PURPOSE: To assess effectiveness, safety and stability of laser epithelial keratomileusis(LASEK), versus conventional photorefractive keratectomy(PRK) for low to moderate myopia. METHODS: 27 patients with a manifest refraction of -3.00 to -6.50 diopters were treated and followed-up for 3 months. In each case, one eye received PRK and the other LASEK. The surgical method and the sequence between the eyes were randomized. Postoperative pain, epithelial healing time, uncorrected visual acuity, manifest refraction, corneal haze and surgical preference were examined after the operation. RESULTS: During a 3-month-follow-up, we found no significant differences in epithelial healing time, uncorrected visual acuity and refractive error. However, LASEK treated eyes had lower postoperative pain scores(P=0.047), and corneal haze scores(1 month; P=0.02) than those of PRK. Seventeen patients(63%) preferred the LASEK procedure. CONCLUSION: LASEK and PRK has an equal effect in correction of myopia, but LASEK reduced incidence of postoperative pain and early postoperative corneal haze. This suggests LASEK can be an alternative procedure for correction of low to moderate myopia.

Effect of Topical 10% Citrate on Corneal Haze after Excimer Laser Photore fractive Keratectomy in Rabbit

It has been known that 10% citrate solution decreases the infiltration of inflammatory cells in severe alkali-burned rabbit eye. The solution was administered topically and its effects on corneal haze and inflammatory cell infiltration were evaluated. Excimer laser photorefractive keratectomy (PRK) was performed on 10 rabbits (20eyes). The solution was administered on the right eye (treated group)and BSS solution on the left eye (control group) of each rabbit immediately before PRK and 6 times after PRK for 24 hours. After 24 hours, 5 rabbits were sacrificed and infiltrating inflammatory cell counting, malondialdehyde (MDA) immunohistochemical staining and quantitative measurement of MDA were done. Corneal haze and other complications were examined at 2, 4 and 8 weeks after PRK with slit-lamp biomicroscope. There was significant decrease of infiltrating inflammatory cells (p=0.047) and cornea haze at 4 weeks after PRK (p=0.015) in treated group. MDA immunohistochemical staining disclosed that tissue damage occurred primarily on the superficial stroma and partially healed epithelium of the ablated cornea. MDA level decreased in 10% citrate treated group compared to control group but the difference was not statistically significant (p=0.21). These data suggest that topical administration of 10% citrate may decrease corneal haze by decreasing infiltration of inflammatory cells after PRK.

The Effect of Amniotic Membrane Gra ft on the Inhibition of Corneal Haze in Rabbit

This study was performed to investigate histopathologically the effect of amniotic membrane graft (AMG)on haze in deep stromal wound of cornea. The excimer laser phototherapeutic keratectomy (PTK)was used to create the wound model of 150 micrometerdepth, 6.0 mmdiameter area in 72 white rabbitsbilaterally.Each eye was randomized to three groups: control (topical antibiotic alone), contact lens application and AMG. Corneal haze,the number of anterior stromal keratocytes and thickness of the regenerated stroma were evaluated after treatments in corneal wound, and also the morphological changes of anterior stroma connected with corneal haze were analyzed. The score of corneal haze in AMG group was significantly lower than those in the others at postoperative 3 days, 2, 4, 6 and 8 weeks. The anterior stromal keratocytes in AMG group significantly remained more than those in the others at postoperative 3 days. The number of keratocytes and thickness of regenerated stromal tissue in wound area of AMG group were statistically lower as compared with those of the other groups at postoperative 4 weeks. The architecture of stromal lamella was most reg-ular in AMG group. Transmission electron microscopic observation demonstrated that the cells in anterior stroma were the active fibroblastic cells with prominent rough endoplasmic reticulum at postoperative 8 weeks. These findings indicate that corneal haze is closely connected with proliferation of corneal stroma , suggesting that AMG on deep corneal stromal wound reduces corneal haze by preventing proliferation of abnormal collagen and fibroblasts at the anterior stroma of the wound area.

Keratocyte Loss in Anterior Stroma of the Rabbit Cornea after Photorefractive keratectomy

This study evaluated the response of the anterior stromal keratocytes in Rabbits following deepithelialization and 3 diopter(37micrometer)- and 12 diopter(99micrometer) PRK. The corneal sections obtained from the operated area on postoperative 3, 7 and 14 days were stained with hematoxylin and eosin. Keratocyte apoptosis were monitored using the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling(TUBEL) staining with ApopTag kit for the corneal section obtained on postoperative 3 day. The corneal haze on postoperative 14 day were graded using a slit lamp biomicroscopy. The number of anterior stromal keratocytes had decreased significantly and positive TUNEL staining was noted in the anterior stroma after PRK and deepithelialization campared with that of controls. The decreased keratocyte numbers were recovered on postoperative 7 day after deepithelialization and on postoperative 14 day after PRK. The newly appeared deratocytes were pyknotic, variable-shaped and crosswisely oriented in appearance, and especially increased following 12 diopter PRK. Both the keratocyte loss and corneal haze grading was increased related to the increased ablation depth after PRK. In conclusion, the loss of anterior stromal keratocytes after PRK is mediated by apoptosis and followed by reactive cellular proliferation might be a important role in the corneal haze.

Comparison of the Effect of Topical Steroid with Nonsteroidal Anti-inflammatory Drugs (NSAIDs) on Corneal Haze and Myopic Regression after Excimer Laser Photorefractive Keratectomy

We wanted to evaluate the effects of topical nonsteroidal antiinflammatory drugs (NSAIDs) on refractive outcome and corneal haze after PRK(photorefractive keratectomy) according to the degree of myopia, and compare their effect with those of topical steroids. We divided our patients into moderate myopes ( OR = -6.0D), and each patient was randomly allocated to one of three drugs for initial management: 0.1% fluorometholone, 0.03% flurbiprofen, 0.1% diclofenac for 4 months after PRK. In moderate myopes, steroid group and NSAIDs group showed no difference in refraction after 6 months, and the subjective haze grading was consistently lower in steroid group after 3 weeks. In high myopes, steroid group and NSAIDs group showed no difference in both refraction and corneal haze after 6 months. Steroid group showed severe myopic regression or corneal haze less frequently than NSAID groups in high myopes. Topical NSAIDs are assumed to be less effective than topical steroids in reducing myopic regression and haze especially in high myopes after PRK.

Effect of the Application of Human Amniotic Membrane on Rabbit Corneal Wound Healing after Excimer Laser Photorefractive Keratectomy

We investigated the influence of amniotic membrane application on corneal wound healing after excimer laser PRK in rabbits. PRK of -9.9D with the optical zone of 5.0mm was performed on each right eye of 34 pigmented rabbits and animals were divided into two groups. Preserved human amniotic membrane was applied in 17 eyes to cover the entire cornea for 48 hours(amniotic group) and the other eyes were used as control group. The area of epithelial defect, inflammatory cell infiltration, the number of anterior stromal keratocyte, and corneal haze were evaluated. The epithelium was healed completely within 3 days in all animals and there was no difference between two groups. At postoperative 12 and 24 hours, in amniotic group, the numbers of stromal inflammatory cells were significantly lower(p=0.009) and the numbers of anterior stromal keratocyte were significantly higher(p<0.05) than those in control group. At postoperative 2, 4, 6, 8, and 12 weeks, the scores of corneal haze in amniotic group were lower than those in control group(p<0.05) and , at postoperative 12 weeks, the number of anterior stromal keratocyte in amniotic group was significantly lower than that in control group(p=0.002). The application of amniotic membrane after PRK reduces keratocyte proliferation and corneal haze during corneal wound healing process, possibly by reducing infiltration of inflammatory cells and loss of keratocyte in the ablation area during the early postoperative period.