Late-onset interface keratitis after uneventful laser in situ keratomileusis

Although there have been many proposed etiologies for interface inflammation after laser in situ keratomileusis, the causative factor(s) remains an enigma. This case of late-onset interface inflammation suggests that the many previously suspected interface contaminants from the surgical environment were not involved. Transformation of a previously inert material to an inflammatory stimulus is proposed as a potential cause; however, a sample of inflammatory focus was not obtained because of the immediate and complete response to frequent topical steroid drops.

Combined refractive lensectomy and laser in situ keratomileusis to correct extreme myopia

Refractive lensectomy followed by laser in situ keratomileusis (LASIK) was performed in both eyes of a severely myopic patient. An uncorrected visual acuity of 20/20 was achieved in the right eye with a manifest refraction of plano -0.25 x 65. Intentional monovision correction of the left eye left a manifest refraction of -0.75 diopter. Best corrected visual acuity improved by 1 Snellen line to 20/20 in both eyes. Follow-up evaluation will be required to assess the long-term refractive stability and the incidence of retinal detachment after combined refractive lensectomy and LASIK.

Central corneal thickness in low-tension glaucoma

BACKGROUND

It is possible that the intraocular pressure (IOP) is underestimated in eyes whose central cornea is thinner than normal. The objective of this study was to determine and establish the significance of central corneal thickness in patients with low-tension (normal-tension) glaucoma compared with those with chronic open-angle glaucoma (COAG) or ocular hypertension and healthy eyes.

METHODS

The study was carried out from February 1998 to May 1999. Central corneal thickness was measured by ultrasonic pachymetry and IOP was measured by Goldmann applanation tonometry in 25 patients with low-tension glaucoma (untreated IOP less than 21 mm Hg with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 80 patients with COAG (untreated IOP 21 mm Hg or greater with evidence of optic nerve head damage and corresponding visual field loss on automated perimetry), 16 patients with ocular hypertension (untreated IOP 21 mm Hg or greater, with normal optic nerve head and no history of glaucoma or elevated IOP, and normal visual field on automated perimetry) and 50 control subjects (untreated IOP less than 21 mm Hg with normal optic nerve head and no history of glaucoma or elevated IOP). Analysis with Pearson's product-moment correlation was performed to determine the correlation of IOP and central corneal thickness, and one-way analysis of variance was used to compare corneal thickness between groups.

RESULTS

The central cornea was significantly thinner in the low-tension glaucoma group (mean 513.2 mu [standard deviation (SD) 26.1 mu]) than in the COAG group (mean 548.2 mu [SD 35.0 mu]) and the control group (mean 556.7 mu [SD 35.9 mu]) (p < 0.001). No significant difference in corneal thickness was found between the COAG and control groups. The ocular hypertension group had significantly thicker corneas (mean 597.5 mu [SD 23.6 mu]) than the three other groups (p < 0.001).

INTERPRETATION

Patients with low-tension glaucoma may have thinner corneas than patients with COAG and healthy subjects. This results in underestimation of their IOP. Corneal thickness should be taken into account when managing these patients to avoid undertreatment.

Pseudo-Fleischer ring after hyperopic laser in situ keratomileusis

A 37-year-old woman had bilateral hyperopic laser in situ keratomileusis (LASIK). Six months postoperatively, an epithelial pigmentation ring pattern was identified on both corneas. The appearance of the ring pattern was similar to the iron deposits of the Fleischer ring of keratoconus. While corneal iron deposits in various patterns have been reported after other forms of ocular therapeutic and refractive surgery, this is the first report of the association between hyperopic LASIK and a corneal iron line, which we have called the "pseudo-Fleischer ring."

Argon laser punctal therapy versus thermal cautery for the treatment of aqueous deficiency dry eye syndrome

BACKGROUND

The objective of this prospective randomized study was to compare the safety and efficacy of argon laser punctal ablation and electrocautery punctal occlusion in the treatment of moderate to severe dry eye and to correlate standard clinical signs with symptoms in these patients.

METHODS

From June 1996 to April 1997 we studied 32 patients (64 eyes) referred to a university-affiliated tertiary care hospital with signs or symptoms of dry eye. Moderate to severe dry eye was confirmed by means of the Schirmer 1 test, fluorescein and rose bengal staining and a visual analogue scale measure of six subjective symptoms. Patients with severe dry eye were randomly assigned to undergo argon laser ablation (17 eyes) or electrocautery occlusion (18 eyes), and were reassessed 2 weeks, 1 month and 6 months after treatment.

RESULTS

Compared with baseline, the laser-treated patients had a peak improvement of 40% in surface wetting at 1 month and improvement of 33% at 6 months; the peak improvement at 6 months in the electrocautery group was 84% (p < 0.05). At 6 months the laser group had a twofold reduction in rose bengal staining, compared with a sevenfold reduction in the electrocautery group (p < 0.05). The electrocautery group had the greatest decrease in fluorescein staining at 6 months (2.8-fold vs. twofold) (p < 0.05). The laser group reported a reduction in symptoms of 31% at 1 month and 14% at 6 months; the corresponding values for the electrocautery group were 55% and 64% (p = 0.02). Posttreatment epiphora was insignificant in both groups. In patients with surface wetting of more than 5 mm at baseline, regular use of Tear-Gel resulted in both objective and subjective improvement.

INTERPRETATION

Although argon laser punctal ablation is a safe method of treating aqueous tear deficiency states, with minimal side effects, both subjective and objective improvement were greater with electrocautery punctal occlusion. Intensive use of Tear-Gel offers benefit to patients with debilitating symptoms in whom aqueous tear production is not severely reduced.

Correlation of intraocular pressure and central corneal thickness in normal myopic eyes and after laser in situ keratomileusis

PURPOSE

To determine the relationship of intraocular pressure (IOP) and central corneal thickness (CCT) in normal myopic eyes and after laser in situ keratomileusis (LASIK).

SETTING

TLC The Windsor Laser Center, Windsor, Ontario, Canada.

METHODS

Intraocular pressure measured by Goldmann applanation tonometry and CCT by ultrasonic pachymetry were determined in a group of untreated corneas of 120 patients (203 eyes) and in 50 patients (85 eyes) pre- and post-LASIK. Statistical analyses were performed with the Pearson correlation coefficient and paired Student t test.

RESULTS

In the untreated group of 288 eyes, mean CCT was 544.0 microns +/- 37.3 (SD) (range 461 to 664 microns) and mean IOP, 15.6 +/- 2.7 mm Hg (range 10 to 24 mm Hg). The correlation between IOP and CCT in this group was highly significant (r = 0.44; P < .0001). The slope was 0.032 mm Hg/micron of CCT or an approximate decrease of 1 mm Hg, for a reduction in CCT of 31.3 microns. In the post-LASIK group, mean CCT dropped approximately 73.0 microns to 479.5 +/- 41.2 microns (range 408 to 503 microns) and IOP dropped to a mean of 13.6 +/- 3.3 mm Hg (range 7 to 22 mm Hg). A significant correlation was found between IOP and CCT after LASIK (r = 0.33; P < .002). The difference between the mean pre- and post-LASIK measurements of applanation IOP was 2.5 mm Hg, which was significant (P < .0001). The post-LASIK slope was 0.027 mm Hg/micron, or a decrease of 1.0 mm Hg per 37.8 microns reduction in CCT.

CONCLUSION

Central corneal thickness is an important variable in the evaluation of applanation IOP and should be included in the assessment of any case of potential glaucoma or ocular hypertension, particularly in eyes with previous photoablative refractive surgery.

Mathematics of laser in situ keratomileusis for high myopia

PURPOSE

To determine the maximal ablation that can be safely performed with laser in situ keratomileusis (LASIK) to maintain long-term corneal integrity.

SETTING

TLC The Windsor Laser Center, Windsor, Canada.

METHODS

The pretreatment protocols for the VISX Star, Summit Omnimed, and Chiron Technolas 116 excimer lasers generally apply 1 to 2 microns per diopter (D) at an optical zone of 3.0 mm or less to avoid the postoperative central islands that can occur with broad-beam excimer lasers. The ablation depth per diopter for the VISX Star, Summit Omnimed, Chiron Technolas 116, and Chiron Technolas 217 excimer lasers ranges from 10 to 24 microns per diopter depending on the size and number of ablation zones and the excimer laser used.

RESULTS

Previous experience with lamellar surgery suggests that at least 250 microns of central posterior stromal tissue should be preserved to maintain long-term corneal integrity and avoid postoperative corneal ectasia. If a 160 microns flap is created for LASIK, the average 550 microns cornea will have 140 microns of corneal stroma available for ablation. Depending on the excimer laser and ablation nomogram used, the maximal LASIK correction for the average cornea ranges from 9.8 to 15.0 D.

CONCLUSION

The preoperative corneal thickness and the depth of the excimer laser ablation must be evaluated before LASIK to ensure that adequate posterior corneal stroma is preserved.

Removal of flap striae following laser in situ keratomileusis

While laser in situ keratomileusis (LASIK) offers advantages over photorefractive keratectomy (PRK), creation of the corneal flap has been associated with postoperative flap striae. These result from misalignment of the corneal flap after flap replacement, movement of the corneal flap during the first postoperative day, or the "tenting effect" of the corneal flap over the ablated stromal bed. Flap striae become more difficult to remove as the postoperative course progresses; therefore, identifying the striae on the first postoperative day is imperative. We describe techniques of flap hydration, refloating, stretching, and smoothing that we use to remove visually significant flap striae.

Conservative photorefractive keratectomy for residual myopia following radial keratotomy

OBJECTIVE

To evaluate the efficacy, predictability, stability and safety of a conservative approach to photorefractive keratectomy (PRK) (treating only 60% to 70% of the residual myopia) for residual myopia following radial keratotomy (RK).

DESIGN

Case series.

SETTING

Laser eye surgery centre in Windsor, Ont.

PATIENTS

Thirty-three eyes of 27 patients with an average age of 40.1 years who underwent PRK between January 1993 and July 1995, 12 months or more after RK. All were followed for at least 12 months after PRK.

OUTCOME MEASURES

Efficacy and safety were assessed by changes in the uncorrected and best corrected visual acuity. Predictability was determined by the proximity of the final result to emmetropia. The stability of the refractive outcome was assessed over the follow-up period.

RESULTS

At 12 months 12 eyes (36%) had 20/20 or better uncorrected visual acuity and 29 eyes (88%) had 20/40 or better uncorrected acuity. Twenty-seven eyes (82%) were within 0.50 D of emmetropia, and 30 eyes (91%) were within 1.00 D of emmetropia. There was a significant change in the mean postoperative spherical equivalent between 1 and 3 months (p < 0.001); however, there was no significant change after this time. Six eyes (18%) had a loss of 2 or more lines of best corrected visual acuity due to corneal haze; however, retreatment reduced this incidence to 9% at 12 months.

CONCLUSIONS

Our results show that conservative PRK for residual myopia following RK is efficacious and predictable and produces stable results. However, the risk of postoperative haze reduces the safety of this procedure.

Quality of corneal donor tissue in the greater-than-75-year age group

PURPOSE

To evaluate the quality of the corneal donor tissue in the greater than 75 year age group with regard to the suitability for transplantation.

METHODS

Fifty consecutive donor corneas from the > 75-year age group were assessed at the Minnesota Lions Eye Bank with slit-lamp examination and specular microscopy.

RESULTS

Thirty-five of the donor corneas were from phakic eyes and 15 were from pseudophakic eyes. There was a highly significant difference (p < 0.05) in the endothelial counts found in the donor corneas from the phakic corneas (average, 2,253.4 +/- 428.9) compared to the pseudophakic eyes (average, 1,701.7 +/- 548.2). There was a highly significant difference (p < 0.05) between the corneal ratings in the phakic and pseudophakic groups, with the phakic group receiving much better (lower) ratings. None of the 15 pseudophakic donor corneas was found to be suitable for transplantation based on a corneal rating of < or = 2, whereas 17 of the 35 phakic eye (48.6%) were found to be suitable for transplantation. From the phakic eyes, 10 of 20 corneas (50.0%) were acceptable in the 76-80-year age group, four of 10 corneas (40.0%) were acceptable in the 81-85-year age group, two of three corneas (66.7%) were acceptable in the 86-90-year age group, and one of two corneas (50.0%) was acceptable in the 91-95-year age group.

CONCLUSION

The results of this laboratory study suggest that many older donor corneas from phakic eyes may be suitable for corneal transplantation.

Recurrent erosion after photorefractive keratectomy

Recurrent erosion of the corneal epithelium has been treated successfully by phototherapeutic keratectomy when convention therapy has failed. We present a case of recurrent corneal erosion occurring 1 year after photorefractive keratectomy in a 55-year-old myopic woman. No corneal abnormalities were previously identified in either the affected or the fellow eye. This case demonstrates the potential for ineffective healing of the corneal epithelial basement membrane complex after excimer laser photorefractive keratectomy.

Intraocular lens implantation in patients with juvenile rheumatoid arthritis

PURPOSE

To study intraocular lens implantation in patients with cataracts associated with juvenile rheumatoid arthritis.

METHODS

We reviewed the records of seven patients (eight eyes) with juvenile rheumatoid arthritis who had undergone cataract extraction by phacoemulsification with intraocular lens implantation. Initial and final visual acuities, preoperative and postoperative medications, and early and late complications were recorded.

RESULTS

Posterior subcapsular cataracts and non-visually disabling peripheral band keratopathy were found in all eyes. The median postoperative follow-up was 17.5 months (mean, 16.6 months; range, nine to 36 months). Five patients were adults, and two patients were less than 10 years old. A best-corrected visual acuity of 20/40 or better was attained in all eyes, and the last recorded visual acuity was 20/40 or better in seven of eight eyes. Early complications included posterior synechiae formation in two eyes, one of which required reoperation. Late complications included visually disabling posterior capsular opacification in one eye and new glaucoma in two eyes. Preoperative corticosteroids were reduced postoperatively in five eyes, were the same in two eyes, and increased in one eye. Persistent postoperative inflammation, posterior synechiae, and a pupillary membrane occurred in one of the children in this study, suggesting that intraocular lens implantation in this age group may have more complications.

CONCLUSIONS

Results of this study suggest that, in selected adults, cataracts caused by juvenile rheumatoid arthritis-associated uveitis can be treated by the standard phacoemulsification technique with intraocular lens implantation and can have excellent results. Intraocular lens implantation in children with juvenile rheumatoid arthritis merits further investigation.

Ocular copper deposition associated with benign monoclonal gammopathy and hypercupremia

The deposition of copper on Descemet's membrane and the anterior and posterior lens capsule with extreme hypercupremia and IgG hypergammaglobulinemia has been previously described with multiple myeloma and pulmonary carcinoma. A 66-year-old man presenting with blurred vision was found to have bilateral golden-brown metallic dust-like deposits on the central region of Descemet's membrane and the anterior and posterior lens capsule. Laboratory investigations revealed an elevated serum copper level 10 times the normal level associated with a monoclonal gammopathy and a normal ceruloplasmin level. Copper binding to the serum proteins was investigated by three biochemical methods. The results demonstrated that the major copper binding fraction in the serum was IgG. N-terminal amino acid analysis of the IgG did not find the sequence of Asp-Ala-His, which has been shown to be a copper binding site in albumin. This is the first report of benign monoclonal gammopathy being associated with the ocular deposition of copper.

Diagnosis of microsporidial keratitis by confocal microscopy and the chromatrope stain

PURPOSE

To illustrate the value of confocal microscopy and chromatrope stain in the diagnosis of microsporidial keratitis.

METHODS

In vivo confocal microscopy was performed on a man with the human immunodeficiency virus who had severe bilateral epithelial keratitis refractory to topical antibacterial medications. The results were compared to conjunctival scrapings stained with the chromatrope-based Weber stain.

RESULTS

Confocal microscopy demonstrated many small, intraepithelial opacities of the corneal epithelium, which were suggestive of Microsporidia. Results of the chromatrope stain of conjunctival scrapings confirmed the diagnosis of microsporidial keratitis.

CONCLUSIONS

Rapid diagnosis allowed prompt initiation of topical fumagillin, which permitted rapid, long-term control of the symptoms of microsporidial keratitis.

Diagnosis of congenital syphilis in adults presenting with interstitial keratitis

In the antibiotic era the ophthalmologist has become less familiar with the diagnosis of congenital syphilis. The recognition of this disease is crucial, as neurosyphilis or cardiovascular syphilis will develop in a substantial number of patients with latent congenital syphilis without the appropriate treatment. We describe eight patients aged 60 years or more who presented with refractive problems in whom congenital syphilis was subsequently diagnosed for the first time. One patient was found to have neurosyphilis and the highest VDRL result ever recorded by the London Public Health Laboratory. Seven patients required extensive antibiotic therapy, and three subsequently underwent successful ocular surgery. These cases illustrate the importance of recognizing this treatable disease.

Phacoemulsification with aspirated or retained Viscoat

Endothelial cell counts, morphology, and 24-hour postoperative intraocular pressure (IOP) changes were measured in 55 consecutive patients (60 eyes) who had uncomplicated phacoemulsification and posterior chamber lens implantation with either aspirated (30 eyes) or retained (30 eyes) Viscoat (sodium chondroitin sulfate-sodium hyaluronate). The surgical technique was standardized in all cases. Endothelial cell loss was almost identical in the aspirated and in the retained groups (8.8% and 8.7%). Postoperative pleomorphism was significantly less in the retained Viscoat group than in the aspirated group, suggesting a possible protective effect of the retained viscoelastic. Corneal thickness increased significantly in the retained Viscoat group, but this was not significant clinically. The retained Viscoat group had more patients with a postoperative IOP greater than 30 mm Hg and a greater mean increase in postoperative IOP, although the difference between the groups was not significant. The IOP changes may have been caused by blockage of the trabecular meshwork by the retained Viscoat. The results suggest that Viscoat can be retained after cataract surgery if the surgeon is prepared for a greater 24-hour postoperative increase in IOP.

Corneal endothelial and intraocular pressure changes after phacoemulsification with Amvisc Plus and Viscoat

A prospective, randomized, observer-marked study was conducted to compare corneal endothelial and intraocular pressure (IOP) changes after cataract surgery with the viscoelastic agents Amvisc Plus and Viscoat. Forty-nine patients (50 eyes) who had uncomplicated phacoemulsification and implantation of a posterior chamber intraocular lens were randomly assigned to either Amvisc Plus (25 eyes) or Viscoat (25 eyes) groups. Surgical technique was rigidly standardized in all cases. No significant difference in endothelial parameters or postoperative IOPs measured at 24 hours, one week, and two months was detected by analysis of variance between the Amvisc Plus and the Viscoat groups. Visualization was difficult with Viscoat because of its tendency to retain bubbles. Phacoemulsification energy was related to a loss of endothelial density, regardless of the viscoelastic used. The postoperative beta blocker may have contributed to the lower average postoperative IOP than has been reported.