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I Süveges

Publications and source records attributed to I Süveges.

At least 19 recordsLinked to original sources
PubMed2003

Influence of LASIK on scanning laser polarimetric measurement of the retinal nerve fibre layer with fixed angle and customised corneal polarisation compensation.

BACKGROUND/AIM: Retinal nerve fibre layer thickness (RNFLT), as measured with scanning laser polarimetry using the fixed angle corneal polarisation compensator (SLP-F), has been found to be reduced after uncomplicated laser assisted in situ keratomileusis (LASIK) compared to the pre-LASIK measurement. Since this virtual RNFLT thinning is attributed to the corneal changes induced by the LASIK, the authors investigated whether customised corneal polarisation compensation (SLP-C), which compensates for the actual corneal polarisation during each measurement, can avoid the LASIK induced, virtual changes of the polarimetric RNFLT values. METHODS: Scanning laser polarimetry using both the SLP-F and SLP-C methods (GDx-Access, software version 5.0) was performed on 15 consecutive healthy subjects with no eye disease who underwent LASIK for ametropia correction. The SLP measurements were performed before the surgery, then on day 1 and day 6 after LASIK. Thickness data from images of one randomly selected eye per subject were analysed using the ANOVA and Scheffe multiple comparison tests. RESULTS: Superior maximum, inferior maximum, normalised superior area, and normalised inferior area (SLP parameters representing the RNFLT at the superior and inferior poles of the optic nerve head) remained unchanged with SLP-C (ANOVA, p>0.05) but decreased (superior maximum, normalised superior area, Scheffe test, p<0.05) or tended to decrease (inferior maximum) after LASIK, when measured using SLP-F. In contrast, certain other parameters-namely, superior ratio and inferior ratio (representing the ratios between the superior or the inferior sector and the temporal sector), maximal modulation, and ellipse modulation decreased with SLP-C (Scheffe test, p<0.05), but remained stable with SLP-F (ANOVA, p>0.05) after LASIK. Superior to nasal ratio, symmetry of the superior and inferior RNFLT as well as the parameter showing the probability of having glaucoma (called "the number") remained unchanged with both types of corneal compensation (ANOVA, p>0.05). With SLP-C the parameter ellipse average thickness increased after LASIK (Scheffe test, p = 0.021). No parameter value altered between day 1 and day 6 after LASIK, for either method. CONCLUSION: The results suggest that the LASIK induced decrease of the polarimetric RNFLT, which is consistently detected with polarimeters when using the fixed angle corneal polarisation compensator, is due to alterations of the corneal polarisation. The use of customised corneal polarisation compensation avoids this virtual decrease of the polarimetric RNFLTHowever, our results suggest an increase of the measured retardation in the temporal quadrant of the SLP-C image after LASIK. Since ratios of parameters using the temporal RNFLT in the denominator are important in the polarimetric glaucoma diagnosis algorithm, their decrease as a consequence of using SLP-C needs further investigation.

Adult↗
PubMed2003

Changes in tear protein pattern after photorefractive keratectomy.

PURPOSE: Changes in tear protein composition of patients who underwent photorefractive keratectomy (PRK) were analyzed. METHODS: Tear samples were obtained from 23 eyes of 23 patients immediately before PRK and on the fourth postoperative day with glass capillaries. Tear proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Digital image analysis and evaluation of the densitometric data of the electrophoretic separations were done with BioDoc-Analyze. RESULTS: Analysis of discriminance found a significant difference in the protein patterns (p < 0.001). This type of analysis of the electrophoretic densitographs uses all peak information simultaneously. A significant decrease (p < 0.005) in three of the main protein peaks--lactoferrin, immunoglobulin A heavy chain, and lysozyme--was also found after PRK. CONCLUSIONS: Excimer laser ablation of the cornea has an acute effect on lacrimal gland protein secretion. Changes in tear composition may lead to feelings of dryness and to a decrease in tear film stability postoperatively.

Adult↗
PubMed2002

Influence of post-LASIK corneal healing on scanning laser polarimetric measurement of the retinal nerve fibre layer thickness.

AIM: To investigate the influence of laser assisted in situ keratomileusis (LASIK) on the values for retinal nerve fibre layer thickness (RNFLT) as measured with scanning laser polarimetry (SLP) during the healing process of the cornea after LASIK. METHODS: SLP with the GDx instrument was performed on 20 consecutive healthy subjects without any eye disease undergoing LASIK for ametropia correction. The SLP measurements were performed before the surgery, and at 1 and 3 days, as well as at 3 months, after LASIK. Thickness data from images of one randomly selected eye per subject were analysed using the ANOVA and Duncan multiple comparison tests. Correlation coefficients between RNFLT data and the treatment parameters were also calculated. RESULTS: Somewhat similar results were found for the different retinal areas. The measured values for superior average RNFLT decreased significantly at all time points compared to the preoperative baseline (p<0.003, Duncan test), but increased significantly between postoperative day 1 and the final visit at 3 months (p=0.025, Duncan test). Inferior average RNFLT in the early postoperative days was significantly smaller than at 3 months after LASIK (p<0.05, Duncan test), and tended to be smaller than at baseline. The thickness values before surgery and at the final visit, however, showed no significant difference (p=0.698, Duncan test) in this region. Ellipse average RNFLT was significantly smaller in the early postoperative days than the baseline value before LASIK. However, the measured value had significantly increased again by the time of the final visit (p<0.02, Duncan test). This value at the final visit showed no difference from the baseline value (p=0.46, Duncan test). The changes in the nasal average and temporal average RNFLT were not statistically significant. No correlation was found between the change in the SLP measured thickness values and central corneal thickness at baseline and its change after surgery, nor with the change in cylindrical correction due to LASIK, or the length of the suction time during surgery (p>0.05 for all correlations). CONCLUSION: The SLP technique is sensitive to the corneal optical properties, and RNFLT as measured with SLP shows changes after LASIK. Most of these changes, however, diminish with time after surgery, and the values tend to return to the preoperative results during the first 3 months of corneal healing following uncomplicated LASIK. It appears that in uncomplicated cases the transient RNFLT changes are artefacts and do not imply pathological thickness alterations due to LASIK.

Adult↗
PubMed2001

Treatment of intraocular pressure elevation after photorefractive keratectomy.

PURPOSE: To study the effect of timolol maleate, dorzolamide, or a combination of both in post photorefractive keratectomy (PRK) eyes with an elevated intraocular pressure (IOP) after topical steroid administration. SETTING: Refractive Surgery Outpatient Department, 1st Department of Ophthalmology, Semmelweis University, Budapest, Hungary. METHODS: Forty-five patients with elevated IOP were randomly enrolled in 3 groups: Group 1 received timolol maleate 0.5% twice a day; Group 2 received timolol maleate 0.5% twice a day and dorzolamide 2% 3 times a day; and Group 3 received only topical dorzolamide 2% 3 times a day. Intraocular pressure was measured 3 days and 1, 3, and 6 weeks after the antiglaucoma medication was started. RESULTS: The mean preoperative IOP was 15.25 mm Hg +/- 1.28 (SD). Following administration of topical fluorometholone, the IOP increased a mean of 27.39 +/- 2.88 mm Hg. Six weeks after the antiglaucoma therapy was started, the mean IOP reduction was 6.6 mm Hg in Group 1, 8.86 mm Hg in Group 2, and 4.64 mm Hg in Group 3. CONCLUSIONS: A combination therapy of timolol 0.5% and dorzolamide 2% was most effective in treating secondary IOP elevation after PRK. Dorzolamide alone did not adequately control secondary post-PRK IOP elevation.

Administration, Topical↗
PubMed1999

[Pathogenesis and conservative treatment of glaucoma].

Glaucoma is a chronic disease which, if not treated, can lead to blindness. The reason for deterioration of function is neuropathia n. optici developed during the disease. Earlier increased ocular tension was considered to be the cause of neuropathia. By now we have realised that increased ocular tension (that above 21 Hgmm) in only one of the risk factors. The decay of optic nerve fibres is caused by circulatory failure on the one hand, and by the necrosis of ganglion cells on the other hand. In the conservative treatment of glaucoma pilocarpin was used earlier but nowdays the first place has been taken over by the group of betareceptor blockers, which are applied twice a day in the form of dropping. If this proves unsatisfactory, the treatment is complemented with carbonanhydrase inhibitor-drops 2-3 times daily. In certain cases this is followed by prostaglandin F2alfa analog drops once a day, dripped in the evening hours. Carboanhydrase inhibitor can be administered per oral as well: 1-2 times weekly. This latter cannot be given continuously: it is only a temporal solution for a few months in addition to other conservative therapy. Cholinerg drops can join in at any time of conservative treatment. The future method of conservative therapy is the combination of drops with varions effect, which decreases the frequency of daily drippings and enhances the efficacy of treatment.

Adrenergic beta-Antagonists↗
PubMed1999

[Results of photorefractive keratectomy after treatment of 2053 eyes].

To evaluate the 12 months refractive results of photorefractive excimer keratectomy (PRK) in high number of eyes with different type of refractive error. Between October 1992 and December 1996. 2053 eyes of 1098 patients were treated with the Aesculap Meditec MEL 60 argon-fluoride excimer laser. Refractive results were concluded at the 12th post-PRK month. The following patient groups were used during the study: Group 1.: Eyes between -1.0 D and -6.0 D (n = 651); Group 2.: -6.0 és -9.0 D (n = 216); Group 3.: Eyes with refractive error above -9.0 D (n = 163); Group 4.: Hypermetrop eyes (n = 160); Group 5.: Eyes with myopic astigmatism (n = 746); Group 6.: Eyes with hypermetropic astigmatism; Group 7.: Pure astigmatism (n = 13). In Group 1. The preoperative average -3.94 +/- 1.3 D refractive error decreased during the 1-year follow-up period to -0.47 +/- 0.54 Dpt; in Group 2. The preoperative -7.65 +/- 1.07 D to -1.16 +/- 1.86 D; in Group 3. The preoperative average -13.58 +/- 3.51 D to -3.11 +/- 2.75 D; in Group 4. The preoperative +4.04 +/- 1.77 D to +1.02 +/- 1.16 D in Group 5. The preoperative -6.06 +/- 2.78 D spherical component decreased to -0.95 +/- 1.33 D-ra, whereas the preoperative cylindrical component from -1.5 +/- 1.08 D to -0.13 +/- 0.58 D; in Group 5. The preoperative +4.57 +/- 1.78 spherical component to +1.13 +/- 1.38 D; whereas the preoperative cylindrical component from +1.57 +/- 0.96 D to +0.38 +/- 0.77 D; in Group 7. The preoperative a -3.98 +/- 1.2 D cylinder decreased to -0.62 +/- 0.75 D cylinder. PRK decreased effectively the preoperative correction need in every treatment group. The results are the better, the smaller the preoperative correction need is.

Adolescent↗
PubMed1999

Central bump-like opacity as a complication of high hyperopic photorefractive keratectomy.

PURPOSE: A new complication is reported in association with high hyperopic excimer laser photorefractive keratectomy. METHODS: One thousand consecutive eyes were treated with a Meditec MEL-60 excimer laser (Meditec Inc, Heroldsberg, Germany) for hyperopic refractive error between +1 diopters and +7 diopters. RESULTS: Three eyes with high hyperopic corrections between +5 and +6 diopters had a central, round bump-like subepithelial scar develop 1 month after hyperopic photorefractive keratectomy, which reduced the uncorrected and spectacle-corrected visual acuity. CONCLUSION: Central bump-like opacity is a new, visually significant complication of unknown origin associated with high hyperopic photorefractive keratectomy. Possible causes of this complication include drying and edema of the cornea as a result of prolonged exposure, interruption of the peripheral superficial nerve plexus affecting the central anterior stroma, and abnormal epithelial or tear film function resulting from excessive central steeping.

Adult↗
PubMed1999

Scanning laser polarimetry via intravitreal silicone oil.

PURPOSE: To investigate whether scanning laser polarimetry, a promising new technique for early detection of glaucomatous nerve fiber loss, is a suitable method to measure retinal nerve fiber layer thickness in eyes with intravitreal silicone oil. PATIENTS AND METHODS: Eleven eyes of 11 consecutive patients two days to 16 months after successful vitrectomy and intravitreal silicone oil injection and 12 eyes of 12 consecutive subjects, who never had any vitreoretinal surgery were examined using the GDx Nerve Fiber Analyzer. Three individual images were computed to a mean image using the software in each case. RESULTS: "Variance", a software-provided parameter, which represents the differences between the individual images used to calculate the mean image was higher in the "silicone oil" group (unpaired t test for different variances, p = 0.02). Good-quality mean images with a "Variance" value similar to that of the control eyes were obtained in seven of the 11 cases. Characteristic artifacts caused by intravitreal silicone oil were observed in five of the 11 cases. CONCLUSION: Successful scanning laser polarimetry is possible after vitrectomy and intravitreal silicone oil injection, and may help to monitor the retinal nerve fiber layer of these eyes in case of silicone oil induced glaucoma.

Adult↗
PubMed1999

Cold pressor test and retinal capillary perfusion in vasospastic subjects with and without capsular glaucoma (a preliminary study).

PURPOSE: Using the cold pressor test the authors investigated the change in retinal and neuroretinal capillary perfusion in vasospastic patients suffering from capsular glaucoma (CG) and in vasospastic control subjects. METHODS: Changes in retinal and optic nerve head capillary perfusion induced by the cold pressor test (one hand immersed in 4 degrees C water for 30 seconds, then in 30 degrees C water for 2 minutes) was measured using the Heidelberg Retina Flowmeter in 4 patients with CG and in 5 healthy control subjects. Previously all subjects showed a reduction of cutaneous capillary flow higher than 70% in the cold pressor test (vasospastic reaction). One eye per subject was investigated. Two images were obtained for each phase (baseline, cold phase and warm phase), and the better quality image from each phase was selected for the measurements. One location on the temporal neuroretinal rim and one location on the temporal retina outside the peripapillary area were selected for the HRF measurements. RESULTS: In the CG group neuroretinal rim "Volume" decreased by 26.05%, "Flow" by 25.82% and "Velocity" by 23.91% (p<0.05), retinal "Volume" decreased by 12.30% (p=0.051), and retinal "Flow" by 22.36% (p=0.01) in the cold phase. All these parameters returned to the corresponding baseline values in the warm phase. In the control group a significant decrease was observed in retinal "Volume" (15.96%), "Flow" (17.81%), and "Velocity" (16.11%) in the cold phase (p<0.05), which diminished in the warm phase but remained still significant for "Flow" and "Velocity". CONCLUSION: Cutaneous cold provocation can induce an immediate decrease in retinal and optic nerve head capillary perfusion at least in a part of the vasospastic subjects with or without capsular glaucoma. This decrease diminishes or disappears quickly when the hand is immersed in warm water. To evaluate the potential role of cold-induced retinal and optic nerve head vasoconstriction in the pathogenesis of capsular glaucoma further investigations are necessary since this reaction was also present in the vasospastic control subjects.

Aged↗
PubMed1998

Excimer laser treatment of hyperopia.

PURPOSE: The aim of this study was to analyse the clinical results of hyperopic photorefractive keratectomy treatments and to compare the results achieved with the usage of different masks. METHOD: 20 eyes of 16 hyperopic patients were treated, using the Aesculap-Meditec MEL60 193nm ArF excimer laser. The mean duration of follow-up was 9.9+/-3.4 months. Statistical comparison of the results with the two masks was made using the unpaired Student t-test. RESULTS: Preoperative mean spherical equivalent was +4.23+/-1.18D, which changed to +0.20+/-0.78D at one month and regressed to +1.23+/-1.27D at the last control examination. After 6 months 60% (12 eyes) had spherical equivalent within +/-1.0D of the attempted correction. The statistical analysis showed no significant difference between the results with the two masks. CONCLUSION: Good preparation for the treatment is of equal importance for the results of the photorefractive keratectomy as compared to the technical circumstances.

Adult↗
PubMed1997

Clinical and morphological response to UV-B irradiation after excimer laser photorefractive keratectomy.

This paper represents an update on a study that has been reported elsewhere (Nagy ZZ et al: Ophthalmology 104:375-380, 1997). The aim of the study was to evaluate the clinical and light- and electron-microscopic effects of ultraviolet-B (UV-B) exposure on the outcome of photorefractive keratectomy (PRK). A total of 42 pigmented rabbits were used in the study. One eye from each of 12 rabbits received a 193 nm 45-microm deep (-5.0 diopters [D]) excimer laser PRK, one eye from each of 12 rabbits received a 135-microm deep (-15.0 D) excimer laser PRK, and one eye from each of 12 rabbits received a 270 microm deep (-30.0 D) excimer laser PRK. Twenty-one days after PRK, six of the laser-treated eyes from each group were exposed to 100 mJ/cm2 UV-B (280-320 nm). The other six rabbits from the PRK groups received no further treatment. One eye from each of six rabbits received only UV-B irradiation, serving as control. Subepithelial haze was evaluated before and after UV-B irradiation. Clinical changes were followed by laser tyndallometry, confocal corneal biomicroscopy, ultrasound biomicroscopy, and endothelial specular microscopy. Corneal morphology was assessed 4, 8, and 12 weeks after UV-B exposure, employing light microscopic and transmission electron-microscopic techniques (TEM). Eyes only exposed to 100 mJ/cm2 UV-B exhibited keratitis for 2 days, but showed no haze and were histologically normal at all time intervals. The PRK-UV-B-irradiated rabbit eyes exhibited a significant increase of stromal haze compared to the eyes receiving PRK alone; this phenomenon correlated with the depth of photoablation. The severity of clinical findings also correlated with the previously attempted photoablation depth; in PRK-UV-B-irradiated eyes the symptoms were much more serious than in eyes treated with PRK alone. Histologically, the main difference between the UV-B-irradiated and nonirradiated-post-PRK eyes was the presence of anterior stromal extracellular vacuolization in the UV-B-exposed eyes. The vacuolated foci were confined to the PRK treatment area, contained increased numbers of keratocytes and showed a disorganization of normal collagen lamellae. Transmission electron microscopy revealed activated keratocytes containing abundant rough endoplasmic reticulum, prominent Golgi zones, and extracellular vacuoles filled with amorphous material. The haze and morphological changes showed a tendency to incomplete resolution over a period of 12 weeks. Ultraviolet-B exposure during post-PRK stromal healing exacerbates and prolongs clinical symptoms and the stromal healing response, which is manifest biomicroscopically by augmentation of subepithelial haze. The findings suggest that excessive ocular UV-B exposure should be avoided during the period of post-PRK stromal repair and that UV-B may modulate the response of tissues to excimer 193 nm, and perhaps, other laser energy in general.

Animals↗
PubMed1997

Ultraviolet-B enhances corneal stromal response to 193-nm excimer laser treatment.

PURPOSE: The purpose of the study was to evaluate the biomicroscopic, light microscopic, and electron microscopic effects of ultraviolet-B (UV-B) exposure on the outcome of photorefractive keratectomy (PRK). METHODS: A total of 24 pigmented rabbits were used in the study. One eye of 16 rabbits received a 193-nm, 45-micron deep (-5.0 diopter) excimer laser PRK. Twenty-one days after PRK, eight of the laser-treated eyes were exposed to 100 mJ/cm2 UV-B (280-315 nm) UV radiation by placing the rabbits in a standard clinically used dermatologic chamber for 7 minutes. Eight PRK-treated rabbits received no further treatment. The remaining eight non-PRK-treated rabbits received 100 mJ/cm2 UV-B only to one eye. Subepithelial haze was assessed before and after UV irradiation. Corneal morphology was assessed 4, 8, 12, and 16 weeks after UV-B exposure, using light microscopic and transmission electron microscopic (TEM) techniques. RESULTS: Untreated eyes exposed to 100 mJ/cm2 UV-B only exhibited photokeratitis for 2 days, but showed no haze and were normal histologically at all intervals. The PRK-treated UV-B irradiated eyes exhibited a significant increase of stromal haze compared to eyes receiving PRK alone. Histologically, the main difference between the UV-B irradiated and nonirradiated post-PRK eyes was the presence of anterior stromal extracellular vacuolization in the UV-B-exposed eyes. The vacuolated foci were confined to the PRK treatment area and showed increased keratocyte density and disorganization of normal collagen lamellae. TEM showed activated keratocytes containing abundant rough endoplasmic reticulum, prominent Golgi zones, and extracellular vacuoles filled with amorphous material. The haze and morphologic changes showed a tendency to incomplete resolution over the period of 16 weeks. CONCLUSIONS: The UV-B exposure during post-PRK stromal healing exacerbates and prolongs the stromal healing response and is manifest biomicroscopically by augmentation of subepithelial haze. The findings suggest that excessive ocular UV-B exposure should be avoided during the period of post-PRK stromal repair and that UV-B may modulate the response of tissues to 193-nm excimer laser and perhaps other laser energy in general.

Animals↗
PubMed1997

Scanning laser polarimetry of the retinal nerve fibre layer in primary open angle and capsular glaucoma.

AIMS: To evaluate the clinical value of scanning laser polarimetry with the nerve fibre analyser type II in primary open angle glaucoma (POAG) and capsular glaucoma. METHODS: Scanning laser polarimetry was performed on one eye of 30 patients suffering from POAG, 25 patients suffering from capsular glaucoma, and on 35 healthy control subjects. The retinal nerve fibre layer (RNFL) thickness values were compared among the groups. Reproducibility of the measurements was calculated and the influence of pilocarpine induced miosis on the results was investigated. RESULTS: RNFL thickness in the superior and inferior sectors, as well as along the total circumference was significantly lower in both glaucoma groups than in the control eyes (p < 0.05). None of the thickness values differed between the two glaucoma groups. Reproducibility was comparable in all groups; the coefficient of variation varied between 3.0% and 8.9% for the different sectors investigated. Miosis had no significant impact either on the thickness values or on the reproducibility (p > 0.05). CONCLUSION: The results suggest that scanning laser polarimetry is a useful method for nerve fibre layer analysis in glaucoma, and that it is not influenced by the pupil size.

Aged↗
PubMed1996

[Phototherapeutic use of excimer laser].

The photorefractive excimer laser is not only able to alter the refractive power of the corneas but also suitable to treat superficial corneal pathologies. Authors performed phototherapeutic keratectomies (PTK) in 80 eyes of 77 patients. The age was on average (+/- S.D.) 49.4 +/- 22.03 years. The follow-up time varied between 3-24 months. All treatments were performed with the Aesculap Meditec MEL 60 ArF excimer laser, working in the 193 nm extreme ultraviolet-C range. Authors conclude that the best postoperative results can be achieved with PTK in cases of recurrent corneal erosions and superficial corneal opacities. Favourable outcome could be expected in treatment of infectious corneal ulcers. In cases of bullous keratopathy the subjective complaints decreased and it was successful to postpone the time of perforating keratoplasty. The PTK is not recommended in case of corneal Bowen disease and recurrent pterygia. A hyperopic shifts was observed in 2 eyes. Besides, the traditional surgical methods the phototherapeutic keratectomy is an important progress in treatment of superficial corneal pathologies. Applying the method, the recurrent erosions healed quicker, in most of the cases the transparency of the cornea could be reestablished in the pupillary area and the need for perforating keratoplasty could be postponed or avoided.

Corneal Diseases↗
PubMed1996

[Examination of subepithelial scar formation after photorefractive keratectomy with the ultrasound biomicroscope].

BACKGROUND: The subepithelial haze and the concomittant refractive regression are the most important complications of photorefractive keratectomies (PRK). The authors examined the subepithelial haze characteristics by ultrasound biomicroscopy (UBM). MATERIALS AND METHODS: Twenty previously photokeratectomized myopic eyes, which showed a certain level of subepithelial scarring have been examined (age: 34.22 +/- 3.57 years, 12 women, 8 men). The range of PRK treatments varied between -4.0 D and -12.0 D. The subepithelial haze graded according to Hanna et al, between 1.0 and 4.0. The UBM examinations were carried out between 1-3 months following PRK with the 50-80 MHz transducer of a Model 840 Zeiss-Humphrey Ultrasound Biomicroscope. RESULTS: The severity of subepithelial haze correlated with the previous photoablation depth. Up till haze graded 2.0 according to Hanna et al. UBM showed loss of Bowman membrane and a slight thinning of the central cornea. Between grade 2.0 and 3.0 the reflectivity of anterior stroma increased, above grade 3.0 a hyperreflective 1/3 anterior stroma with irregular borders were observed. CONCLUSION: Haze phenomen graded below 2.0 is not observable with UBM. Haze, graded more than 2.0 caused an increase of anterior stormal reflectivity. In more serious cases the 1/3 of the anterior stroma might be affected. The UBM-method with a 50-80 MHz probe is suitable to document and follow the serious haze phenomen after photoablations.

Adult↗
PubMed1996

Morphological response to UV-B irradiation after excimer-laser photorefractive keratectomy.

The purpose of this study was to evaluate the morphological effects of UV-B exposure on the outcome of photorefractive keratectomy (PRK). A total of 42 pigmented rabbits were used in the study. In all, 1 eye of 12 rabbits received a 193-nm and 45-micron-deep (-5.0-D) excimer-laser PRK, 1 eye of 12 rabbits received a 135-micron-deep (-15.0-D) excimer-laser PRK and 1 eye of 12 rabbits received a 270-micron-deep (-30.0-D) excimer-laser PRK. At 21 days after PRK, six of the laser-treated eyes from each group were exposed to 100 mJ/cm2 UV-B (280-320 nm) light by placement of the rabbits in a standard clinically used "dermatological chamber" for 7 min. One eye of six rabbits received only UV-B light, serving as a control. The other six rabbits from the PRK groups received no further treatment. Subepithelial "haze" was evaluated before and after UV irradiation. Corneal morphology was assessed at 4, 8 and 12 weeks after UV-B exposure by light microscope and transmission electron microscope techniques (TEM). Eyes exposed to 100 mJ/cm2 UV-B light exhibited only keratitis for 2 days but showed no haze and were histologically normal at all time points. The PRK-treated, UV-B-irradiated rabbit eyes exhibited a significant increase in stromal haze as compared with the eyes receiving PRK alone; this phenomenon correlated with the depth of photoablation. Histologically, the main difference observed between the UV-B-irradiated and nonirradiated post-PRK eyes was the presence of anterior stromal extracellular vacuolization in the UV-B-exposed eyes. The vacuolated foci were confined to the PRK treatment area, contained increased numbers of keratocytes and showed a disorganization of normal collagen lamellae. TEM revealed activated keratocytes containing abundant rough endoplasmic reticulum, prominent Golgi zones and extracellular vacuoles filled with amorphous material. The haze and morphological changes showed a tendency towards incomplete resolution over a period of 12 weeks. UV-B exposure during post-PRK stromal healing exacerbates and prolongs clinical symptoms and the stromal healing response in rabbits, which is manifested biomicroscopically by augmentation of subepithelial haze. The findings suggest that excessive ocular UV-B exposure should be avoided during the period of post-PRK stromal repair (at least 3 months) and that UV-B light may modulate the response of tissues to 193-nm excimer and, perhaps, other laser energy in general.

Animals↗
PubMed1995

[Experience with excimer laser photorefractive keratectomy].

UNLABELLED: The correction of refractive errors based on superficial ablation of the cornea has a couple of years long history. Authors performed photorefractive laser surgery with the Aesculap Meditec MEL 60 ArF excimer laser in 221 eyes of 147 patients. The follow-up time varied between 2-24 months, average 8 months. They have treated the following groups: 1. group: 0-6.0 D; 2. group: -6.5-9.0 D; 3. group: eyes with refractive error above -9.5 D; 4. group: hypermetropic eyes; 5. group: eyes with astigmatism. RESULTS: In the 1. group the average -4.58 +/- 1.25 D refractive error decreased to -0.19 +/- 0.53 D in the follow-up time; 2. group: from -7.46 +/- 1.22 D to -0.45 +/- 0.83 D; 3. group: -13.76 +/- 5.46 D to -1.52 +/- 1.74; 4. group: +428 +/- 1.6 D to +0.91 +/- 2.41 D; 5. group; from -6.74 +/- 2.81 D sph -2.3 +/- 1.54 cyl to -0.51 +/- 1.3 D sph -0.54 +/- 1.06 D cyl. According to their experiences they conclude: the best results have been achieved in the first two groups and in eyes with astigmatism (1., 2., 5. groups). In severe myopia cases postoperative correction is usually needed, which is significantly smaller than the preoperative spherical correction. The method is able to change the refractive power of the cornea and provides an efficient alternative to the spectacles and contact lenses.

Adult↗