Biomedical subjects

T Oshika

Publications and source records attributed to T Oshika.

At least 19 recordsLinked to original sources

PubMed2006

Advanced glycation end product deposits in climatic droplet keratopathy.

BACKGROUND: Climatic droplet keratopathy (CDK), known as spheroid degeneration of the cornea, is one of the most frequent degenerative corneal disorders affecting visual function. However, the histochemical nature of the deposits seen in CDK is still unclear. AIM: To investigate the pathogenesis of CDK, we investigated the immunohistochemical localisation of advanced glycation end products (AGEs) in surgical specimens of CDK. METHODS: Immunohistochemical localisation of N(epsilon)-(carboxymethyl)-l-lysine (CML), N(epsilon)-(carboxyethyl)-l-lysine (CEL), pyrraline, pentosidine and imidazolone was examined in three corneas with CDK, six corneas with bullous keratopathy and three corneas without any corneal diseases. RESULTS: In all the specimens with CDK, immunoreactivity was strong in CML, moderate in pyrraline and pentosidine, and weak in imidazolone. Immunoreactivity was absent in CEL. In contrast, no immunoreactivity to CML, pyrraline, pentosidine, imidazolone or CEL was detected in corneas with bullous keratopathy, or in corneas without any corneal diseases. CONCLUSIONS: CDK is caused by an aggregation of AGE-modified proteins. The result is consistent with etiological findings that ultraviolet irradiation and ageing, both of which are accelerators of AGE formation, are closely related to the development of CDK.

Antibodies, Monoclonal↗

PubMed2006

Clinical evaluation of cornea pseudoguttata.

AIM: To report on cornea pseudoguttata which occurred in 44 eyes from 40 patients. METHODS: In 3521 consecutive patients seen at a local eye clinic, eyes were examined with a slit-lamp biomicroscope in specular illumination. When guttate appearance was found, specular microscopy was performed. RESULTS: Cornea pseudoguttata was found in 44 eyes of 40 patients (1.1%). All patients had some form of anterior-segment ocular diseases, including keratitis (corneal infiltration) with contact lens wear (n = 16), epidemic keratoconjunctivitis (n = 8), corneal epithelial defect (n = 6), superficial punctate keratitis (n = 4), corneal foreign body (n = 3), keratitis of unknown causes (n = 3), corneal ulcer (n = 2), herpetic keratitis (n = 1), and iritis (n = 1). Six eyes were lost to follow-up, but in the remaining 38 eyes, cornea pseudoguttata completely resolved as the primary anterior-segment diseases subsided. Specular microscopy, measured after resolution of cornea pseudoguttata, showed that corneal endothelial cell density was not different between the affected and contralateral healthy eyes. CONCLUSION: Cornea pseudoguttata is commonly found in cases with corneal infiltration and inflammation. These results indicate that cornea pseudoguttata is reversible in its nature and resolves completely without any damage to the corneal endothelial cells.

Adolescent↗

PubMed2006

Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration.

AIM: To investigate the influence of tilt and decentration of scleral-sutured intraocular lenses (IOLs) on ocular higher-order wavefront aberrations. METHODS: In 45 eyes of 36 patients who had undergone scleral suture fixation of posterior chamber IOL, tilt and decentration of IOLs were determined by Scheimpflug videophotography, and higher-order aberration for a 4-mm pupil was measured using the Hartmann-Shack aberrometer. In another 100 eyes of 100 patients after standard cataract surgery with posterior chamber IOL implantation, ocular higher-order aberration was measured. RESULTS: In eyes with scleral-sutured IOL, the mean (SD) tilt angle and decentration were 4.43 degrees (3.02 degrees ) and 0.279 (0.162) mm, respectively. Ocular coma-like aberration in the sutured IOL group was 0.324 (0.170) microm, which was significantly greater than that of the standard cataract surgery group (0.169 (0.061) microm, p<0.001, Student's t test). No significant difference was found in ocular spherical-like aberration between the sutured IOL group (0.142 (0.065) microm) and standard surgery group (0.126 (0.033) microm; p = 0.254). In the sutured IOL group, IOL tilt significantly correlated with ocular coma-like aberration (Pearson's correlation coefficient r = 0.628, p<0.001), but no significant correlation was found between IOL tilt and ocular spherical-like aberration (r = 0.222, p = 0.175). The IOL tilt did not correlate with corneal coma-like (r = 0.289, p = 0.171) and spherical-like (r = 0.150, p = 0.356) aberrations. The IOL decentration did not correlate with any higher-order aberrations. CONCLUSION: In eyes with scleral-sutured posterior chamber IOL, tilting of the lens induces considerable amount of ocular coma-like aberrations.

Aged↗

PubMed2006

Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal eyes.

AIMS: To assess the retention and removal properties of a new viscous dispersive ophthalmic viscosurgical device (OVD), DisCoVisc, in comparison with those of cohesive (Provisc), dispersive (Viscoat), and viscoadaptive (Healon5) OVDs. METHODS: In 20 porcine eyes, cataract surgery was simulated using one of the four OVDs which were stained with fluorescein for better visualisation. Three parameters were measured. Firstly, the presence/absence of OVDs in the chamber at the completion of phacoemulsification was recorded. Secondly, the time until the OVDs were completely removed from the anterior chamber using the phaco needle was measured. Thirdly, after intraocular lens (IOL) implantation, the time needed to completely remove the OVDs from the chamber with irrigation/aspiration tip was recorded. RESULTS: At the completion of phacoemulsification, the OVDs retained in 0% (0/5) for Provisc, 80% (4/5) for Healon5, 100% (5/5) for DisCoVisc, and 100% (5/5) for Viscoat. The retention of OVDs during phacoemulsification was greatest with Viscoat followed by, in descending order, DisCoVisc, Healon5, and Provisc. The removal of OVDs after IOL implantation took longest with Viscoat followed by Healon5, DisCoVisc, and Provisc. CONCLUSION: The viscous dispersive DisCoVisc showed excellent retention during phacoemulsification, while its removal after IOL implantation was very easy. When compared with the viscoadaptive Healon5, DisCoVisc was retained better in the chamber and was easier to remove. These features of DisCoVisc should be highly advantageous when considering covering the entire cataract surgery procedure with a single OVD.

Animals↗

PubMed2005

Blinking and superficial punctate keratopathy in patients with diabetes mellitus.

AIM: To evaluate blinking patterns in patients with diabetes mellitus and whether blinking contributes to the formation of superficial punctate keratopathy in diabetic patients. METHODS: We examined 163 patients with type II diabetes mellitus and 76 without diabetes. Blinks were recorded, analysed using six parameters, and compared between patients with and without diabetes. Multivariate regression analysis was performed to assess the influence of other ocular factors, such as status of tear lipid layer, tear breakup time, corneal sensitivity, the result of cotton thread test, or blinking rate related to superficial punctate keratopathy. RESULTS: In patients with diabetes, the average mean and maximum interblinking times were longer, the average coefficient of variation of interblinking time was higher, and the average blinking rates were lower than those in patients without diabetes. Multivariate regression analysis revealed that the status of tear lipid layer and tear breakup time were significantly relevant to superficial punctate keratopathy (P < 0.01). CONCLUSION: Interblinking time was longer in diabetic patients, resulting in a decreased blinking rate. The prevalence of superficial punctate keratopathy cannot be predicted from blinking patterns in patients with diabetes.

Aged↗

PubMed2004

Specular microscopic study of X-ray-irradiated rabbit cornea.

PURPOSE: To investigate the influence of ionizing radiation on the corneal epithelium and endothelium of rabbit eyes. METHODS: Five healthy mature albino rabbits were unilaterally irradiated with 20 Gy of X-rays (250 kV, 12 mA). Slit-lamp biomicroscopic observation and specular microscopic examination of the corneal epithelium and endothelium were carried out before and 1, 4, 8, 12, 16, 20, 24, and 36 weeks after irradiation. We evaluated mean area of the superficial corneal epithelial cells, mean area and the percentage of hexagonal cells of the corneal endothelial cells, and corneal thickness. The statistical difference between the irradiated and control eyes was assessed using paired t-test. RESULTS: All animals developed cataract within 24 weeks. Slit-lamp biomicroscopy showed no apparent corneal abnormalities over the 36-week follow-up period. Specular microscopy revealed a significant enlargement of the superficial corneal epithelial cells from 4 to 12 weeks after irradiation (P<0.01), which disappeared at 16 weeks post-irradiation. Specular microscopy of the corneal endothelium showed enlargement and morphological alterations of the cells beginning 8 weeks after irradiation (P<0.05). These changes persisted throughout the study period. There were no statistically significant changes in corneal thickness. CONCLUSION: After X-ray radiation of 20 Gy, transient damage occurred in the corneal epithelium, while delayed and irreversible changes were seen in the endothelium.

Animals↗

PubMed2004

Comparison of corneal thickness measurements using Orbscan II, non-contact specular microscopy, and ultrasonic pachymetry in eyes after laser in situ keratomileusis.

AIMS: To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis (LASIK). METHODS: Central corneal thickness was measured in 203 eyes after myopic LASIK. Orbscan II scanning slit topography (Bausch & Lomb), SP-2000P non-contact specular microscopy (Topcon), and ultrasonic pachymetry (Tomey) were used in this sequence. RESULTS: Three devices gave significantly different corneal thickness readings (p<0.0001, repeated measure analysis of variance). The measurements of Orbscan II (445.6 (SD 60.0) microm) were significantly smaller than those of noncontact specular microscopy (467.9 (SD 40.2) micro m; p<0.0001, Tukey multiple comparison) and ultrasonic pachymetry (478.8 (SD 41.9) microm; p<0.0001). The value obtained with SP-2000P non-contact specular microscopy was significantly smaller than that taken with ultrasonic pachymetry (p<0.001). There were significant linear correlations between scanning slit topography and non-contact specular microscopy (Pearson's correlation coefficient r = 0.912, p<0.0001), non-contact specular microscopy and ultrasonic pachymetry (r = 0.968, p<0.0001), and ultrasonic pachymetry and scanning slit topography (r = 0.933, p<0.0001). CONCLUSION: In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness. Non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.

Adult↗

PubMed2004

A prospective, randomised comparison of single and three piece acrylic foldable intraocular lenses.

AIMS: To compare the postoperative performance of single and three piece acrylic foldable intraocular lenses (IOLs). METHODS: 20 patients underwent bilateral cataract surgery with a single piece SA30AL IOL in one eye and a three piece MA30BA IOL in the other eye. The eyes were randomly assigned to either a single or three piece lens. The amount of IOL decentration and tilt, area of anterior capsule opening, and degree of posterior capsule opacification were measured using the Scheimpflug anterior segment analysis system (Nidek EAS-1000). Visual acuity and contrast sensitivity were examined. Measurements were performed by masked examiners before and 1 day, 1 week, 1, 3, 6, and 18 months after surgery. RESULTS: There were no significant differences between the two groups (p>0.05, paired t test) in the amount of IOL decentration, IOL tilt, area of anterior capsule opening, degree of posterior capsule opacification, best corrected visual acuity, and contrast sensitivity throughout the 18 month follow up period. CONCLUSION: The single and three piece acrylic foldable IOLs are equally stable in the eye after surgery.

Acrylic Resins↗

PubMed2001

Expression of vascular endothelial growth factor C and vascular endothelial growth factor receptor 3 in corneal lymphangiogenesis.

Lymphangiogenesis has been reported in vascularized corneas. However, the molecular mechanisms of lymphangiogenesis in the cornea are still unclear. Since lymphatic vessels may contribute to a decreased success rate of keratoplasty in vascularized cornea by accelerating antigen recognition and graft rejection, elucidation of the mechanisms of corneal lymphangiogenesis will facilitate the inhibition of lymphatic vessels and may improve the outcome of keratoplasty. This study aimed to examine the expression of vascular endothelial growth factor-C (VEGF-C), which is the only endogenous lymphangiogenic factor reported so far, and one of its receptors, vascular endothelial growth factor receptor-3 (VEGFR-3), in corneal lymphangiogenesis. A rat model was used in which silver nitrate application resulted in corneal circumferential neovascularization. The presence of lymphatic vessels in the rat injured cornea was examined with electron microscope. Corneal VEGF-C and VEGFR-3 mRNA levels were quantified with competitive reverse transcription polymerase chain reaction (RT-PCR), and VEGF-C and VEGFR-3 proteins were studied in situ using immunohistochemical analysis. Electron microscopy revealed lymphatic vessels in the vascularized rat corneas. Competitive RT-PCR demonstrated that the expression of VEGF-C mRNA in the rat cornea was normally absent, and was dramatically up-regulated 3 days after the injury, which gradually decreased. The VEGFR-3 expression in the rat cornea was minimally detected before the injury and was up-regulated 3 and 7 days after the injury. It was also minimally detected 2 and 4 weeks after the injury. In immunohistochemical analysis of the rat cornea 3 days after the injury, VEGF-C was mainly detected in inflammatory cells, and VEGFR-3 was demonstrated in several new vessels in the corneal stroma. These data suggest that VEGF-C and VEGFR-3 are pathophysiologically relevant endogenous factors in corneal lymphangiogenesis.

Animals↗

PubMed2001

Glycemic control and lens transparency in patients with type 1 diabetes mellitus.

PURPOSE: To assess quantitatively the cumulative effect of hyperglycemia on lens transparency in patients with juvenile type 1 diabetes mellitus. METHODS: Subjects were 30 patients (30 eyes) with type 1 diabetes mellitus who had well-documented records on the duration of diabetes mellitus and condition of glycemic control from the onset. They were 35 years of age or younger (mean, 26.0 years), had a history of type 1 diabetes mellitus at least 5 years (mean, 8.4 years), had corrected visual acuity of 20/20 or better, and showed no clinically apparent cataract on slit-lamp examination. Twenty-one eyes of 21 subjects served as age-matched normal controls. They were 35 years of age or younger (mean, 25.7 years), had no diabetes mellitus, had corrected visual acuity of 20/20 or better, and showed no signs of cataract on slit-lamp examination. The degree of lens opacity was quantified using the anterior eye segment analysis system based on the Scheimpflug principle. An index was created to represent the cumulative effect of long-term glycemic control (hyperglycemic accumulation) by multiplying the average hemoglobin A(1c) value and the number of months from the onset. RESULTS: The patients with diabetes mellitus exhibited significantly greater degree of lens opacity than the normal controls (P =.017, Mann-Whitney U-test). Among the patients with diabetes mellitus, the lens opacity was greater in eyes with retinopathy than those without retinopathy (P =.011). Multiple regression analysis revealed that only the index of hyperglycemic accumulation significantly correlated with the degree of lens opacity (P =.042). CONCLUSION: Accumulated effect of hyperglycemia is related to the lens transparency in patients with diabetes.

Adult↗

PubMed2001

Anterior capsular contraction after cataract surgery in vitrectomized eyes.

PURPOSE: To assess the contraction of continuous curvilinear capsulorhexis after cataract surgery in eyes with past pars plana vitrectomy. METHODS: In a prospective study, 16 eyes of 16 patients underwent phacoemulsification and implantation of a foldable acrylic intraocular lens after pars plana vitrectomy. Eyes after intensive or repeated vitrectomy were not included. Twenty eyes of 19 patients served as age-matched controls. Aqueous flare intensity was measured using the laser flare-cell meter 1 year after surgery. The area of anterior capsular opening (ACO) was determined by diaphanoscopy using the anterior eye segment analysis system EAS-1000 at 1 day and 1 year postoperatively. RESULTS: There was no significant difference in the mean ACO area between the vitrectomy and control groups both at 1 day and 1 year postoperatively. Aqueous flare intensity 1 year after surgery was slightly higher in the vitrectomy group, but the difference was not statistically significant. CONCLUSION: Eyes after simple vitrectomy are not at a higher risk of ACO contraction following cataract surgery.

Aged↗

PubMed2001

Factors affecting the forward shift of posterior corneal surface after laser in situ keratomileusis.

PURPOSE: To evaluate the anteroposterior movement of the corneal back surface after laser in situ keratomileusis (LASIK). DESIGN: Retrospective noncomparative case series. PARTICIPANTS: One hundred ninety-six eyes of 120 subjects with myopic refractive errors of -2.0 to -12.5 diopters. INTERVENTION: LASIK was performed. Corneal topography of the posterior corneal surface was obtained with the scanning slit topography system before and 1 month after surgery. MAIN OUTCOME MEASURES: The amount of forward shift of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affect the forward shift of the posterior corneal surface. RESULTS: After surgery, the posterior corneal surface displayed mean forward shift of 40.9 +/- 24.8 micrometer. Explanatory variables relevant to the forward shift of corneal posterior surface were, in the order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.561, P < 0.0001), preoperative corneal thickness (B = -0.176, P = 0.00096), and preoperative intraocular pressure (B = 1.676, P = 0.0053). Preoperative refraction and achieved myopic correction showed collinearity with the amount of laser ablation. CONCLUSIONS: LASIK induces a forward shift of the cornea. Eyes with thinner corneas, higher intraocular pressure, and higher myopia requiring greater laser ablation are more predisposed to the anterior shift of the cornea.

Adult↗

PubMed2001

Mechanical detachment of the anterior hyaloid membrane from the posterior lens capsule.

OBJECTIVE: To investigate the incidence of spontaneous detachment of the anterior hyaloid membrane from the posterior lens capsule and to explore the possibility of surgical separation of the anterior hyaloid membrane. DESIGN: Prospective nonrandomized interventional comparative trial and comparative human tissue study. PARTICIPANTS: Thirty-eight eyes of 32 patients undergoing primary pars plana vitrectomy combined with cataract extraction and intraocular lens implantation and 3 eye bank eyes for histopathologic examination. METHODS: The anterior hyaloid membrane and posterior lens capsule were observed with a fiberoptic endoscope. Surgical separation of the anterior hyaloid membrane was attempted by either the hydrodissection method before cataract extraction (18 eyes) or the direct suction method after cataract extraction (20 eyes). In eye bank eyes, histopathologic examination was performed with (one eye) and without (two eyes) surgical separation of the anterior hyaloid membrane. MAIN OUTCOME MEASURES: Incidence of spontaneous detachment and success rate of surgical detachment of the anterior hyaloid membrane. RESULTS: No eye displayed spontaneous detachment of the anterior hyaloid membrane. Using the hydrodissection method, complete detachment of the anterior hyaloid membrane was achieved in 10 eyes (55.6%), partial detachment was attained in 2 eyes (11.1%), and detachment was not induced at all in 6 eyes (33.3%). With the direct suction method, the anterior hyaloid membrane was completely separated from the posterior lens capsule in 10 eyes (50%), partially detached in 10 eyes (50%), and not detached at all in any eye. The direct suction method had a significantly higher success rate than the hydrodissection method (P < 0.001, chi-square test). In eye bank eyes, the surgical manipulation induced complete separation of the anterior hyaloid membrane from the lens capsule. CONCLUSIONS: Spontaneous detachment of the anterior hyaloid membrane from the posterior lens capsule is very rare. Under endoscopic observation, surgical detachment of the anterior hyaloid membrane was possible in half of the patients.

Adult↗

PubMed2001

Corneal irregular astigmatism and contrast sensitivity after photorefractive keratectomy.

OBJECTIVE: To investigate the relation between contrast sensitivity and corneal irregular astigmatism in eyes after photorefractive keratectomy (PRK). DESIGN: Prospective observational case series. PARTICIPANTS AND CONTROLS: Seventy-nine eyes without corneal haze 6 months or more after PRK and 30 normal control eyes. METHODS: Videokeratography was taken with TMS-1 (Computed Anatomy Inc. New York, NY), and contrast sensitivity for day and night vision was measured using a Multivision Contrast Tester 8000 (Vistech Consultants, Inc., Dayton, OH). MAIN OUTCOME MEASURES: Regular and irregular astigmatism (asymmetry and higher order irregularity components) were computed using Fourier series harmonic analysis of the videokeratography data. Area under the log contrast sensitivity function (AULCSF) was calculated from the contrast sensitivity data taken at five spatial frequencies. RESULTS: After PRK, AULCSFs were significantly smaller for day vision (P = 0.007, unpaired t test) and night vision (P = 0.020) compared with normal controls. AULCSFs for day vision were significantly negatively correlated with asymmetry (Pearson's correlation coefficient, R = -0.23, P = 0.049) and higher order irregularity (R = -0.33, P = 0.004) components but not with the regular astigmatism component (P > 0.3). AULCSF for night vision correlated significantly with asymmetry (R = -0.31, P = 0.013) and higher order irregularity (R = -0.30, P = 0.016) components but not with the regular astigmatism component (P > 0.3). CONCLUSIONS: Corneal irregular astigmatism after PRK significantly influences contrast sensitivity.

Adult↗

PubMed2001

Piggyback foldable intraocular lens implantation in patients with microphthalmos.

PURPOSE: To evaluate the clinical results of phacoemulsification and implantation of 2 foldable acrylic intraocular lenses (IOLs) in microphthalmic eyes. SETTING: University of Tokyo School of Medicine, Tokyo, Eguchi Eye Hospital, Hakodate, and Osaka Rosai Hospital, Osaka, Japan. METHODS: This study comprised 5 eyes of 3 patients whose manifest spherical equivalent was +10.5 to +18.0 diopters (D) and axial length was 15.79 to 16.82 mm. After phacoemulsification, 2 foldable acrylic IOLs with a mean power of +43.0 D +/- 9.5 (SD) (range +32.0 to +55.0 D) were implanted in the capsular bag. RESULTS: There were no significant intraoperative complications, and there was significant improvement in uncorrected and best corrected visual acuities after surgery. The spherical equivalent decreased significantly; however, the postoperative refraction was considerably more hyperopic than predicted in all eyes. Except for posterior synechias in 2 eyes and slight interlenticular opacification in 2 eyes, no major postoperative complications occurred during the mean follow-up of 14.8 months. CONCLUSIONS: Implanting 2 piggyback IOLs was beneficial in eyes with an extremely short axial length. However, the current system of lens power calculation markedly underestimates the required lens power, resulting in a hyperopic refractive error after surgery. The benefits of in-the-bag placement of 2 foldable lenses are questionable.

Acrylic Resins↗

PubMed2001

Secondary closure of neodymium:YAG laser posterior capsulotomy.

A 67-year-old man reported reduced vision after cataract surgery and neodymium:YAG (Nd:YAG) laser posterior capsulotomy. The diagnosis was complicated due to severe glistenings within the optic of an acrylic foldable intraocular lens (IOL), proliferation of lens epithelial remnants over the capsulotomy opening, and presumed vitreous opacity. Although IOL exchange surgery was considered, a second Nd:YAG laser intervention successfully removed the proliferated lens materials and restored the visual acuity. The glistenings were not the cause of the reduced vision.

Aged↗

PubMed2001

Effect of subconjunctival steroid injection on intraocular inflammation and blood glucose level after cataract surgery in diabetic patients.

PURPOSE: To prospectively evaluate the usefulness of a subconjunctival steroid injection given at the completion of cataract surgery in patients with diabetes mellitus. SETTING: University of Tokyo School of Medicine, Tokyo, Kaiya Eye Clinic, Hamamatsu, and Jyosai Hospital, Tokyo, Japan. METHODS: One hundred four eyes of 104 diabetic patients having routine small incision cataract surgery were randomized into 2 groups. One group received a subconjunctival injection of dexamethasone and the other group did not. Aqueous flare intensity was measured with the laser flare meter preoperatively and 1, 2, 5, 7, and 14 days postoperatively. Another 19 diabetic patients having routine cataract surgery were randomized to receive a subconjunctival steroid injection or not; blood glucose concentration was measured 4 times a day for 3 days postoperatively. RESULTS: There was no significant difference between the 2 groups in aqueous flare values at any postoperative time. The subconjunctival steroid injection induced a transient but significant increase in blood glucose on the day of surgery. CONCLUSION: A subconjunctival steroid injection given at the completion of cataract surgery in diabetic patients had no beneficial effects.

Aged↗

PubMed2001

Relation between corneal haze and transforming growth factor-beta1 after photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE: To investigate the relation between corneal haze formation and transforming growth factor-beta (TGF-beta) after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan. METHODS: White rabbits were divided into 4 groups, with each group receiving 1 of the following surgeries: manual epithelial abrasion, PRK, lamellar keratotomy, or LASIK. The degree of corneal haze was quantitatively analyzed by measuring the light scattering intensity of corneas before and 4 and 12 weeks after surgery. The expression of type IV collagen and TGF-beta1 in the corneas at baseline and at 4 weeks was examined immunohistochemically. RESULTS: The light scattering intensity was significantly greater 4 and 10 weeks after PRK. In contrast, epithelial abrasion, lamellar keratotomy, and LASIK did not influence the light scattering intensity of the corneas. Type IV collagen was detected in the basal lamina of the corneal epithelium and in Descement's membrane in the normal cornea. After epithelial abrasion, there was no change in the distribution of type IV collagen. Four weeks after PRK, the expression of type IV collagen was detected in the subepithelial layer of the laser-ablated area. Four weeks after lamellar keratotomy, type IV collagen was linearly and fragmentarily detected in the corneal stroma. Four weeks after LASIK, type IV collagen was linearly and continuously detected in the corneal stroma and was detected slightly in the subepithelial region of the laser-ablated area. In the normal corneas, the expression of TGF-beta1 was not detected in the keratocytes. Four weeks after PRK, the expression of TGF-beta1 increased in the keratocytes that proliferated in the subepithelial fibrous layer. In contrast, epithelial abrasion, lamellar keratotomy, and LASIK did not change the expression pattern of TGF-beta1 in the keratocytes. CONCLUSION: The multiplier effect of epithelial abrasion and excimer laser ablation in PRK may increase the expression of TGF-beta1 in keratocytes and induce corneal haze.

Animals↗