A Case of Paradoxical Worsening of Dural-Sinus Arteriovenous Malformation Syndrome after Neurosurgery

The authors present a case of a patient with the syndrome of paradoxical worsening of dural-sinus cavernous arteriovenous malformation which was a iatrogenic consequence of embolization of the basal branches of a dural shunt with Yvalon. It is presumed that the thrombogenous Yvalon reached the basal branches of the medial meningeal artery to the superior ophthalmic vein, where it caused complete thrombosis. The impaired ocular and orbital venous outflow caused a dramatic worsening of the ocular congestive symptoms: venous stasis retinopathy with dilated veins, flame-and dot-shaped hemorrhages and a secondary increase in intraocular pressure. The diagnosis of thrombosis of the entire superior ophthalmic vein was confirmed by color Doppler imaging. The mechanism is discussed. Although the ocular pathology is usually self-limiting following the establishment of collateral venous outflow channels, in view of the patient's serious congestive ocular symptoms argon laser photocoagulation and conservative antiglaucomatous local therapy were applied. Once orbital collateral venous drainage was established, the ocular symptoms improved. In the one-year follow-up there was no other complication.

[Atypical acute syphilitic posterior placoid chorioretinitis]

Syphilis is an infectious disease that can cause a wide variety of ocular signs. One of the rarest manifestations of ocular syphilis is acute syphilitic posterior placoid chorioretinitis (ASPPC). We report the case of an immunocompetent 38-year-old woman diagnosed with unilateral, atypical, acute syphilitic posterior placoid chorioretinitis. Fundoscopic examination revealed a yellow-white, subretinal, placoid lesion at the posterior pole, which is typical sign of ASPPC. In the periphery of the retina, multifocal choroiditis was also found. Fundus and angiographic changes in ASPPC may mimic other chorioretinal diseases. Accurate diagnosis of ASPPC as a presenting sign of syphilis is important for the prompt initiation of systemic antibiotic treatment.

[Bilateral simultaneous central retinal vein occlusion in protein S deficiency]

CASE REPORT

This article reports a case of bilateral simultaneous central retinal vein occlusion (CRVO) and protein S deficiency. The 27-year-old male patient presented with a sudden decrease in vision in both eyes. The patient's medical history documented the death of his father at the age of 33 years due to pulmonary embolism. Thrombophilia screening revealed protein S deficiency.

OBJECTIVES

We report this case to emphasize that in any case of young onset retinal vein occlusion, protein S deficiency should be suspected.

CONCLUSIONS

Thrombophilia assays and taking a thorough medical history should be performed.

[Two cases of phototherapeutic keratectomy treatment of the recurrent corneal erosion caused by alkali burn]

BACKGROUND

Four eyes of two patients were injured simultaneously by industrial alkali while working. One eye of both patients healed without later consequences.

PATIENTS AND METHODS

Two eyes were treated with phototherapeutic keratectomy (PTK) because of recurrent corneal erosion syndrome caused by alkali burn.

RESULTS

In both cases reepithelisation of the cornea was completed by the end of the 1st postoperative week, the injured persons were able to work again. No recurrence was experienced in the next 6 months of follow-up.

CONCLUSION

With these cases the authors would like to draw attention to the possible complications, as well as the importance of careful balancing and adequate management.

Corneal topography parameters after superior clear corneal incision cataract surgery in arcus lipoides

PURPOSE

To compare changes in corneal topographic parameters after cataract surgery in eyes with different severities of arcus lipoides.

METHODS

Fourty eyes of 40 patients (23 women, 17 men, age 71.3+/-20.4 years, range 40 to 89 years) were studied prospectively in a consecutive, non-interventional, comparative series of cases. Eyes were classed in three groups (0 to 2) according to the assessed grade of arcus lipoides (none, <180 degrees, >180 degrees). Corneal topography (Tomey TMS-2) was performed preoperatively and at 1 and 10 days and 1 and 3 months following cataract surgery (superior 4.0 mm clear corneal incision, no suture). Keratometric astigmatism (Dcyl), surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) were evaluated for the different groups and time-points, using the Kruskal-Wallis, Wilcoxon, and Mann-Whitney statistical tests.

RESULTS

No significant preoperative difference was found in mean Dcyl, SRI, or PVA; preoperative SAI was lower in Group 1. Postoperatively Dcyl was increased at day 1 in Groups 1 and 2, and remained higher in Group 2 until month 1. At month 3 significant differences among Groups 0, 1, and 2 disappeared.

CONCLUSIONS

The 4.0 mm superior clear corneal incision is a safe method for cataract surgery in the presence of arcus lipoides. This procedure induces greater corneal astigmatism, surface irregularity, and lower PVA in the early postoperative period in cases with arcus lipoides than in normal corneas. Concerning final results, wound healing was not affected by greater severity of arcus lipoides, although stabilization of the corneal surface tended to be slower.

Scanning laser polarimetry of retinal nerve fibre layer thickness after laser assisted in situ keratomileusis (LASIK): stability of the values after the third post-LASIK month

BACKGROUND

Monitoring the retinal nerve fibre layer thickness (RNFLT) is essential in the diagnosis and treatment of glaucoma. In a previous study we found that a decrease of the polarimetric RNFLT observed in the early period after laser-assisted in situ keratomileusis (LASIK) disappears or tends to disappear by the third post-LASIK month.

PURPOSE

To study the stability of the "recovered" polarimetric retardation values between the third and twelfth month after LASIK.

METHODS

Scanning laser polarimetry (SLP) with the classic GDx Nerve Fiber Analyzer was performed on 13 consecutive healthy subjects with no eye disease who underwent LASIK for ametropia correction. Measurements were performed preoperatively, then at 3 and 12 months postoperatively.

RESULTS

Inferior, temporal and nasal average thickness as well as ellipse average thickness and average thickness showed no difference among the three time points (ANOVA, p > 0.05). Superior average thickness was significantly smaller both at three months (Sheffe test, p =0.008) and 12 months (p =0.006) than before LASIK. However, no difference was seen between the values measured at three months and at 12 months after LASIK (p =0.997). A statistically significant interaction between treatment type (myopic or hyperopic correction) and the change of retardation was found for the superior average thickness (two-way ANOVA, p =0.016). In this quadrant the RNFLT values of the myopic eyes decreased between the baseline and the month 3 measurements but became stable after that; the retardation of the hyperopic eyes remained unchanged throughout.

CONCLUSION

RNFLT measured with the classic GDx device after LASIK shows transient changes probably due to the LASIK-induced alteration of the polarization and the healing process. The polarimetric RNFLT values, however, become stable by the third post-LASIK month, and show no further change until the end of the first year after LASIK. Baseline SLP measurements for long-term glaucoma follow-up can be obtained from the third post-LASIK month onwards.

[Unilateral ptosis in the background of unilateral corneal arcus lipoides -- a case report]

BACKGROUND

Arcus lipoides corneae is a common bilateral degenerative disorder with ageing but only rarely occurs unilaterally. Clinically visible cream-coloured ring-shaped corneal opacities are caused by excessive lipoid deposits in the corneal stroma. Our aim is to discuss theoretical aspects of the possible impact and pathomechanism of unilateral ptosis in unilateral arcus lipoides.

CASE REPORT

The authors report the case of a 70-year-old female patient who was treated for chronic pancreatitis and hyperlipoproteinemia. She had congenital ptosis on the left side, and an arcus lipoides corneae in her left eye. The patient underwent extracapsular cataract extraction, and irregular high-grade astigmatism developed. An irregularity of the wound healing was apparent from the keratometric values, which decreased after removal of the corneal sutures.

CONCLUSION

The known etiological factors of unilateral arcus lipoides, like contralateral stenosis of the internal carotid artery, traumatic or iatrogenic hypotony, chronic iridocyclitis of the eye were absent in our patient.

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.

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.

Photorefractive Keratectomy for Hyperopia in 800 Eyes With the Meditec MEL 60 Laser

PURPOSE

To evaluate the refractive results of 800 hyperopic eyes undergoing PRK treatment.

METHODS

Eight hundred hyperopic eyes were treated with PRK. An Aesculap-Meditec MEL 60 scanning ArF excimer laser used. Treatment Group 1 consisted of eyes with a preoperative refractive error of +3.50 D or less (n = 482) and Group 2, of +3.75 D or more (n = 318).

RESULTS

Preoperatively, Group 1 required an average correction of +2.88+/-1.34 D and Group 2 required +5.64+/-2.96 D. One year after PRK, average residual correction was +1.26+/-1.24 D in Group 1, and in Group 2, +2.46+/-1.84 D. In Group 1, uncorrected visual acuity (UCVA) was 20/40 or better in 88.4% (426/482); 20/20 or better in 75.7% (365); 2.1% (10/482) of eyes lost 2 lines, 2.1% (10/482) gained 2 lines; 3.1% (15/482) gained 2 or more lines of BSCVA; 74.4% (359/482) of eyes were within +/-0.50 D of target correction and 84.8% (408/482) were within +/-1.00 D. In Group 2, 47.5% (151/318) had UCVA of 20/40 or better; 34.2% (109/318) saw 20/20 or better uncorrected; 19.1% (61/318) lost 2 lines; 11.6% (37/318) lost 3 lines; none of the eyes gained 2 or more lines of BSCVA; 22.3% (71/318) were within +/-0.50 D and 46.8% (149/318) were within +/-1.00 D of target correction. Refractive stability was achieved after 6 months; a slight regression after 6 months was still observed. In Group 1, 10.5% (42/482) and in Group 2, 21.6% (69/318) complained of problems with daytime vision (glare and ghost image); during night-driving in Group 1, 17.6% (85/482) and in Group 2, 40.5% (129/318) had problems.

CONCLUSION

PRK with the Aesculap-Meditec MEL 60 scanning ArF excimer laser offered the best long-term results with +3.50 D or less preoperative refractive error. With higher corrections, regression, decrease in BSCVA, and daytime visual problems were encountered.

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.

Photorefractive Keratectomy for Astigmatism With the Meditec MEL 60 Laser

PURPOSE

To evaluate the results of photorefractive keratectomy (PRK) in eyes treated with astigmatic refractive errors.

METHODS

Nine hundred forty eyes were treated with the Aesculap Meditec MEL 60 ArF excimer laser. Treatment groups were: Group 1 (n=746) eyes with compound myopic astigmatism, Group 2 (n=104) eyes with compound hyperopic astigmatism, Group 3 (n=75) eyes treated for mixed astigmatism, and Group 4 (n=15) eyes with simple myopic astigmatism (negative cylinder).

RESULTS

In Group 1, the preoperative spherical equivalent refraction of -6.10 D with an average of -1.50 D cylinder decreased to -0.95 D with -0.13 D cylinder; uncorrected visual acuity (UCVA) of 20/40 or better was achieved in 86% (642/746 eyes); 20/20 or better in 58% (433/746 eyes); 0.8% (6/746 eyes) lost two lines of spectacle-corrected visual acuity (SCVA); 74% (552/746 eyes) were within +/-0.50 D and 93% (694/746 eyes) were within +/-1.00 D of target refraction. In Group 2, preoperative mean +4.57 D spherical equivalent refraction with an average of +1.57 D cylinder decreased to +1.13 D with +0.38 D cylinder; UCVA of 20/40 or better was achieved in 84% (87/104 eyes); 20/20 or better in 46% (48/104 eyes); 14,4% (15/104 eyes) lost two or more lines of SCVA; 52% (54/104 eyes) were within +/-0.50 D and 82% (85/104 eyes) were within +/-1.00 D of target refraction. In Group 3, mean preoperative -4.20 D cylinder and +3.00 D spherical equivalent refraction decreased to -0.50 D cylinder and -0.50 D spherical equivalent refraction; UCVA of 20/40 or better was achieved in 83% (62/75 eyes); 20/20 or better in 32% (24/75 eyes); 13.3% (10/75 eyes) lost two or more lines of SCVA. In Group 4, mean preoperative -3.98 D cylinder decreased to -0.62 D cylinder; UCVA of 20/40 or better was achieved in 60% (9/15 eyes); none of the eyes achieved 20/20 or better; SCVA remained stable in 6.6% (1/15 eyes) and decreased two or more lines in 20.0% (3/15 eyes); 20% (3/15 eyes) were within +/-0.50 D and 53.3% (8/15 eyes) were within +/-1.00 D of target refraction.

CONCLUSION

PRK with the Meditec MEL 60 laser produced the best results in eyes with compound myopic astigmatism (Group 1). In all other groups, results were less predictable.

Photorefractive Keratectomy for Myopia With the Meditec MEL 70^sub G-Scan^ Flying Spot Laser

PURPOSE

To evaluate the efficacy, predictability, stability, and safety of the Meditec MEL 70G-Scan flying spot excimer laser.

METHODS

One hundred thirty myopic eyes were treated with the Aesculap Meditec Mel 70G-Scan ArF flying spot excimer laser with photorefractive keratectomy (PRK). Patient groups: low myopia (Group 1) from -1.50 to -6.00 D (90 eyes), medium myopia (Group 2) from -6.10 to -9.00 D (31 eyes), high myopia (Group 3) from -9.10 to -14.00 D (9 eyes).

RESULTS

At 12 months in the low myopia group, uncorrected visual acuity (UCVA) of 20/40 or better was achieved in 95.5% (86 eyes), 20/20 or better in 77.7% (70 eyes); 2.2% (two eyes) lost two or more lines of best spectacle-corrected visual acuity (BSCVA); 73.3% (66 eyes) were within +/-0.50 D of the target correction and 98.8% (89 eyes) were within +/-1.00 D. In the medium myopia group, UCVA of 20/40 or better was achieved in 74.2% (23 eyes), 20/20 or better in 25.8% (eight eyes); 3.2% (one eye) lost two lines, 61% (19 eyes) were within +/-0.50 D of desired correction and 83.8% (26 eyes) were within +/-1.00 D. In the high myopia group, UCVA of 20/40 or better was achieved in 22.2% (two eyes); 20/25 or better in 11.1% (one eye); none of the eyes achieved 20/20 UCVA; 22.2% (two eyes) lost two lines of BSCVA; 44.4% (four eyes) were within +/-0.50 D and 66.6% (six eyes) were within +/-1.00 D of the target correction. Refractive stability was achieved between 3 and 6 months. Increased intraocular pressure was detected overall in 7.69%.

CONCLUSIONS

The results of predictability, safety, and efficacy in low and medium myopia with the Meditec MEL 70G-Scan flying spot excimer laser were good, but poorer predictability, regression, and a significant loss of BSCVA were observed in the high myopia group.

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.

[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.

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.

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.

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.

[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.

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.

Keratocytes produce thrombospondin 1: evidence for cell phenotype-associated synthesis

Immunochemical techniques were used to determine whether cells of the avascular corneal stroma (keratocytes) have the ability to synthesize thrombo- spondin 1 (TSP1), a glycoprotein originally described in platelets and more recently implicated in regulating cell behavior (e.g., migration) during wound repair in vascular tissue. Immunoprecipitation experiments with metabolically labeled cells showed that bovine keratocytes in preconfluent cultures produced TSP1, but de novo TSP1 production could not be detected in confluent keratocyte cultures. Immunofluorescence studies of the preconfluent cells revealed that the keratocyte TSP1 was distributed in perinuclear granules and peripheral foci. TSP1 expression also was observed in keratocytes cultured in a collagen matrix model of stromal wound healing and, in this model, immunogold labeling revealed TSP1 foci on keratocyte surfaces adjacent to collagen fibers in the matrices. TSP1 expression was not observed in the syncytial keratocytes of normal bovine cornea. The results indicate that keratocytes have the ability to synthesize TSP1, and do so in vitro under conditions which simulate corneal stroma repair, but suggest that keratocytes in a syncytial arrangement (as in the normal cornea) do not make TSP1. TSP1 may play a role in corneal pathologies which induce keratocytes to change from a syncytial to a wound repair phenotype, such as mechanical damage to the stroma. Local production of TSP1 might provide an alternative source to platelet-derived TSP1 during nonvascularized stromal tissue repair.

[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.

[Experience with excimer laser photorefractive keratectomy]

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.

The role of excimer laser photorefractive keratectomy in treatment of residual myopia followed by radial keratotomy

Authors report a case with photorefractive retreatment after previous radial keratotomy (RK) due to a -4.5 D refractive error. The indication of retreatment was a -2.75 D regression during the one-year follow-up time after RK. The photorefractive keratectomy (PRK) was performed with the Aesculap Meditec MEL 60 excimer laser. During the 8-month follow-up time, in the retreated eye the uncorrected visual acuity was fully recovered, no regression was experienced. The excimer laser appears to be a good method to correct refractive errors, regressed or retained from previous refractive procedures due to the possibility of precise calibrating and the moderate ablation depth compared to the total thickness of the cornea.

Intraoperative pachymetry during excimer photorefractive keratectomy

The evaluation of pre- and intraoperative corneal thickness is of great importance in photorefractive surgery and in planning phototherapeutic treatments. The authors evaluated 14 eyes with Humphrey ultrasonic pachymeter Model 855 during photorefractive keratactomies (PTK). All treatments were performed with the Aesculap Meditec MEL 60 ArF excimer laser. The preoperative uncorrected visual acuity averaged 0.078 +/- 0.068. The average of preoperative correction used to obtain the best corrected visual acuity was: -6.11 +/- 3.70. The average preoperative corneal thickness was found at 548.14 +/- +/- 24.58 microns; the average thickness of the mechanically removed epithelium was: 51.5 +/- 1.49 microns. After PRK the corneal thickness decreased to 440.78 +/- 33.2 microns. The thickness of the photoablated corneal tissue was on the average 55.86 microns measured by the ultrasound pachymeter. The pachymeter values correlated well with the average of 53.21 +/- 30.19 microns thickness change calculated by the excimer laser combi modul display monitor. The authors conclude, that ultrasound pachymeter is suitable for evaluating pre- and intra-operative corneal thickness. Echobiometric pachymetry is valuable in planning and executing phototherapeutic treatment. It permits the surgeon to assess intraoperatively the thickness of the already ablated corneal tissue and reduce the risk of postoperative refractive changes. The method is also suitable for controlling the photorefractive calibration of the excimer laser.

Experiences with photorefractive excimer laser treatment in compound myopic astigmatism

The invention of excimer lasers and different masks in order to treat refractive failures has opened a new era in refractive surgery. The refractive grading, the ablation effect, which can be controlled within one micrometer, and the design of a special mask made possible so-called "corneal sculpting" in compound astigmatism. The authors evaluated their experiences on 27 myopic compound astigmatic eyes. The average age of the patients was 28.67 +/- 9.78 years and the average preoperative uncorrected visual acuity was 0.06 +/- 0.04. The spherical component averaged -6.74 +/- 2.81 D and the cylindrical component averaged -2.3 +/- 1.54 D (the preoperative correction needed to obtain the best corrected visual acuity). Postoperatively, the uncorrected visual acuity improved to 0.65 +/- 0.26. To obtain the best corrected postoperative visual acuity an average -0.51 +/- 1.06 D sph and an average -0.54 +/- 1.06 D cyl component was needed. The authors conclude that ArF excimer laser treatment is able to alter both of the spherical and cylindrical components of the eye toward emmetropia. The lower the degree of preoperative compound myopic astigmatism, the better are the chances of postoperative emmetropia. No serious complications were met during the follow-up period.

Posterior avulsion of the optic nerve due to deceleration trauma

A patient with complete transection of the optic nerve (posterior avulsion) and explosion of the eyeball, due to an attempted suicide is reported. The symptoms, mechanism of injury and therapeutic possibilities in complete transection and in partial posterior optic nerve avulsions are discussed. Although this case ended up with enucleation, the partial avulsions are not without hope. The importance of team-work is emphasized in polytraumatic patients.

Excimer laser in the treatment of recurrent pterygia

Authors report two cases of multiple recurrent pterygia which were treated with the usual surgical technique (sec. Arlt) and a subsequent excimer laser treatment. In case one they used slit mode, in the other case spot mode was applied. The superficial phototherapeutic ablations were performed with an Aesculap Meditec MEL 60 193-nm Arf excimer laser. During a one year follow-up period recurrence was experienced in both cases. According to the literature in primary pterygia the excimer laser might be helpful in the reepithelization by smoothing the corneoscleral surface. In recurrent cases, however, the glycosaminoglycane content of the collagen fibres are lower in the corneal scar tissue, so due to the impaired hydratation, the fluency of the excimer laser might fail to ablate the pathological surface structures. On the other hand, in recurrent cases the corneoscleral barrier function is also heavily impaired, so the conjunctival epithelial cells are not able anymore to recognize the corneoscleral border. It is concluded that in recurrent cases the excimer laser phototherapeutic treatment is of less value than in primary pterygia.

Refractive results after photorefractive excimer laser treatment in mild myopic and in mild hyperopic eyes

Evaluation of 12-month results of photorefractive keratectomies (PRK) performed in low myopic (0 to -6.0 D) and low hyperopic (0 to +6.0 D) eyes. Myopic and hyperopic PRK treatments with the Aesculap Meditec MEL 60 ArF excimer laser. Prospective study, 30 eyes per group. The change in best corrected visual acuity (VA), refraction required, uncorrected VA and the postoperative haze were compared at the 12th postoperative month. The average preoperative correction in the low myopic eyes (Group I) was -4.65 +/- 1.24 D, which decreased to -0.17 +/- 0.56 D during the follow-up. In mild hyperopic eyes (Group II) the preoperative refraction was +3.9 +/- 0.93 D and decreased to +1.23 +/- 1.59 D post-PRK. Comparing the pre- and postoperative average best corrected VA values, there was no statistical change in either group. In the low myopic group all eyes had a 20/40 or better uncorrected VA, in hyperopic eyes 11 had a VA of 20/40 or better, four had a worse uncorrected VA. In Group I, 86.6% of the eyes were within +/-1.0 D of the intended refraction at 12 months postoperatively. In Group II, 46.7% of the eyes were within +/-1.0 D of final refraction. There were no intergroup differences in subjective complaints, reepithelization and average postoperative haze. Both methods are able to alter the refractive power of the cornea toward emmetropia. The predictability of the method was to be found higher in cases of mild myopia than in mild hyperopia. The upper limit of myopia is above -6.0 D, but in hyperopia, with the present technical facilities, good postoperative results can be obtained only as far as +4.25 D of preoperative refractive error.

Changes of the corneal endothelium after ultraviolet-B exposure in previously photokeratectomized eyes

The photorefractive effect of excimer lasers is based on an interaction between the 193-nm ultraviolet-C laser beam and the stromal chromophore molecules. Recently, in some patients an increase of subepithelial haze and a regression of refractive effect has been observed following suntanning (UV-B exposure). The aim of the study was to find out the possible endothelial damage caused by photoablation with increasing depth and the effect of subsequent UV-B exposure on previously photokeratactomized eyes. Altogether 12 chinchilla rabbits were treated. Four animals received a -5.0 D PRK; four animals a -15.0 D PRK and four animals a -30.0 D PRK treatment. The endothelial average number, size and variation were determined two weeks post-PRK. Three weeks following PRK, a half of the animals received a 1 J/cm2 ultraviolet-B radiation in a constant dermatological UV-chamber. The endothelial morphology was measured the same way with automated specular microscopy two weeks after UV-B irradiation. After PRK treatment there was no statistically demonstrable change in endothelial morphology. On the other hand, after UV-B radiation all eyes showed a decrease in endothelial number and an increase in size and variation. The ratio of hexagonality decreased, and endothelial rosette formation appeared. The early morphological changes resembled the physiological aging changes. Conditions (deep stromal photoablation, cumulative effect of suntanning or solarium treatments) may exaggerate the physiological aging processes leading to subsequent pleomorphism, polymegatism and cell loss. This may accelerate corneal dysfunction.

Retinoscopy after excimer laser photorefractive treatments

Photorefractive keratectomy (PRK) is capable of changing the refractive power of the human cornea. Retinoscopy is an objective method of measuring the refractive power of the eye. The authors performed PRK in 28 myopic eyes with the Aesculap Meditec MEL 60 ArF excimer laser. During a prospective study, the subjective and objective refractive power of the eyes were assessed and compared 6 months after PRK. The average preoperative refractive error was: -5.11 +/- 2.51 D and -5.08 +/- 2.20 D on the right side (n = 16) and on the left side (n = 12), respectively. In order to obtain the best corrected visual acuity 6 months after PRK, the right and left eyes needed an average of -0.09 +/- 0.26 D and -0.33 +/- 0.64 D postoperative correction, respectively. The postoperative refractive change could be verified with the retinoscopy at +/-0.5 D accuracy. The authors describe a double refractive corneal ring after PRK, which may disturb retinoscopy. The post-PRK refractive change can be verified by retinoscopy. Postoperative funduscopy, fundus photography and possible future retinal procedures were not disturbed by the double corneal refractive rings in myopic eyes.