Mark Speaker

Serious Complications of Topical Mitomycin-C after Pterygium Surgery

BACKGROUND The use of topical mitomycin (mitomycin-C) as a medical adjunct to pterygium and glaucoma surgery is increasing. METHODS The authors report on a series of 10 patients who experienced serious, vision-threatening complications associated with the use of this drug after pterygium surgery. RESULTS Complications included severe secondary glaucoma (4 patients), corneal edema (3 patients), corneal perforation (1 patient), corectopia (2 patients), iritis (8 patients), sudden onset mature cataract (2 patients), scleral calcification (1 patient) and incapacitating photophobia and pain (8 patients). Two patients required penetrating keratoplasties and a third required three lamellar keratoplasties. Another patient underwent four additional surgeries including a conjunctival Z-plasty, scleral patch grafting, and conjunctival autografting before his intractable pain and photophobia resolved 15 months after the original surgery. Because of these complications, 6 patients required a total of 20 return visits to the operating room after their original pterygium surgery. In 5 eyes, visual acuity remained at 20/200 or less. Three of the six patients with the most severe complications had concomitant chronic external diseases (rosacea [3 patients], ichthyosis [1 patient], keratitis sicca [1 patient]). CONCLUSION The authors urge extreme caution in the use of mitomycin. If mitomycin is used, the lowest possible concentration should be applied for the shortest time period in an effort to avoid these complications. A prospective multicenter study of the ophthalmic use of this medication is needed.

Prophylaxis of endophthalmitis with topical povidone-iodine

The authors conducted an open-label nonrandomized parallel trial to examine whether the preoperative application of povidone-iodine to the ocular surface reduces the incidence of endophthalmitis after intraocular surgery. During an 11-month period, topical 5% povidone-iodine was used to prepare the conjunctiva in 1 set of 5 operating rooms, while silver protein solution was used in another set of 5 rooms. In all cases, surgeons continued to use their customary prophylactic antibiotics. A significantly lower incidence of culture-positive endophthalmitis (P less than 0.03) was observed in the operating rooms using povidone-iodine (2 of 3489 or 0.06%) compared with those using silver protein solution (11 of 4594 or 0.24%). Use of topical povidone-iodine in over 3000 cases was not associated with any adverse reactions. In a majority of the observed cases of endophthalmitis, some form of intraoperative communication with the vitreous cavity existed.

Late Bleb-related Endophthalmitis after Trabeculectomy with Adjunctive 5-Fluorouracil

The incidence of late-onset bleb-related endophthalmitis was evaluated retrospectively in 229 consecutive trabeculectomies performed with adjunctive 5-fluorouracil (5-FU) therapy. Mean follow-up was 23.7 +/- 16.3 months (range, 3 to 60 months). Thirteen eyes (5.7%) of 11 patients developed bleb-related endophthalmitis an average of 25.9 +/- 17.4 months (range, 5 to 58 months) after surgery. Infection occurred in 9 of 96 (9.4%) procedures performed from below and in 4 of 133 (3.0%) procedures performed superiorly (P = 0.05, Fishers exact test). The relative risk of bleb-related endophthalmitis in trabeculectomy from below versus above is 4.0 after adjustment for age and sex (95% confidence interval = 1.1, 14.8). Trabeculectomy with adjunctive 5-FU performed from below carries an increased risk of late bleb-related infection. The incidence of late bleb-related endophthalmitis after 5-FU trabeculectomy appears to be higher than that for trabeculectomy without adjunctive 5-FU injections.

A Case-control Study of Risk Factors for Postoperative Endophthalmitis

The authors conducted a case-control study to identify risk factors for postoperative endophthalmitis. Fifty-four cases of patients who developed endophthalmitis after intraocular surgery at the New York Eye and Ear Infirmary during the period from January 1988 through October 1990 were identified. A control group of 228 patients was randomly selected from the 24,105 patients who underwent intraocular surgery during this same period. Logistic regression analysis identified significant independent risks associated with intraoperative communication with the vitreous cavity (risk ratio 13.7, P less than 0.001) and use of an intraocular lens with haptics made of polypropylene (risk ratio 4.5, P = 0.007). The study predicts that there would be approximately 700 fewer cases of postoperative endophthalmitis annually in the United States (approximately a 50% decrease in incidence) if intraocular lenses with haptics made of polymethyl-methacrylate, rather than polypropylene, were used exclusively.

A Case-control Study of Risk Factors for Intraoperative Suprachoroidal Expulseve Hemorrhage

The authors performed a case-control study of risk factors for suprachoroidal expulsive hemorrhage (SEH); the study involved 68 SEH cases at their institution from 1981 to 1986. The authors examined 113 variables in the study group and a procedure-matched control group of 217 patients randomly selected from the 35,459 patients who underwent intraocular surgery during this period, and subjected them to bivariate and conditional logistic regression analysis. The incidence of SEH was 0.19% overall, 0.16% for lens-related procedures, 0.15% for glaucoma surgery, 0.41% for retinal and vitreous procedures, and 0.56% for keratoplasty. Statistically significant risk factors for SEH in age-adjusted bivariate analyses included: glaucoma (P less than 0.0001), increased axial length (P less than 0.0001), elevated intraocular pressure (IOP) (P less than 0.0001), generalized atherosclerosis (P = 0.007), and elevated intraoperative pulse (P = 0.0001). Conditional logistic regression analysis with frequency matching on age identified significant independent risks associated with a history of glaucoma, elevated IOP, increased axial length, and intraoperative tachycardia. One of the models predicts a 752-fold increased theoretical relative risk of SEH for a patient with axial length greater than or equal to 25.8 mm, a history of glaucoma, preoperative IOP greater than 18 mmHg, and intraoperative pulse greater than or equal to 85 beats per minute. The visual outcome after SEH was best in cases of extracapsular cataract extraction (ECCE), compared with other procedures. Results suggest that attention to multiple preoperative and intraoperative ocular and systemic variables may allow identification and prophylaxis of patients at risk for SEH.

Intraocular lens calculations after refractive surgery

Purpose: To evaluate the effect of refractive surgery on intraocular lens (IOL) power calculation, compare methods of IOL power calculation after refractive surgery, evaluate the effect of pre‐refractive surgery refractive error on IOL deviation, review the literature on determining IOL power after refractive surgery, and introduce a formula for IOL calculation for use after refractive surgery for myopia. Setting: Laser & Corneal Surgery Associates and Center for Ocular Tear Film Disorders, New York, New York, USA. Methods: This retrospective noncomparative case series comprised 21 patients who had uneventful cataract extraction and IOL implantation after previous uneventful myopic refractive surgery. Six methods of IOL calculation were used: clinical history (IOLHisK), clinical history at the spectacle plane (IOLHisKs), vertex (IOLvertex), back‐calculated (IOLBC), calculation based on average keratometry (IOLavgK), and calculation based on flattest keratometry (IOLflatK). Each method result was compared to an “exact” IOL (IOLexact) that would have resulted in emmetropia and then compared to the pre‐refractive surgery manifest refraction using linear regression. The paired t test was used to determine statistical significance. Results: The IOLHisKs was the most accurate method for IOL calculations, with a mean deviation from emmetropia of −0.56 diopter ±1.59 (D), followed by the IOLBC (+1.06 ± 1.51 D), IOLvertex (+1.51 ± 1.95 D), IOLflatK (−1.72 ± 2.19 D), IOLHisK (−1.76 ± 1.76 D), and IOLavgK (−2.32 ± 2.36 D). There was no statistical difference between IOLHisKs and IOLexact in myopic eyes. The power of IOLflatK would be inaccurate by −(0.47x + 0.85), where x is the pre‐refractive surgery myopic SE (SEQm). Thus, without adjusting IOLflatK, most patients would be left hyperopic. However, when IOLflatK is adjusted with this formula, it would not be statistically different from IOLexact. Conclusions: For IOL power selection in previously myopic patients, a predictive formula to calculate IOL power based only on the pre‐refractive surgery SEQm and current flattest keratometry readings was not statistically different from IOLexact. The IOLHisKs, which was also not statistically different from IOLexact, requires pre‐refractive surgery keratometry readings that are often not available to the cataract surgeon.

Comparative evaluation of refractive surgery candidates with Placido topography, Orbscan II, Pentacam, and wavefront analysis

PURPOSE: To study the role of the Pentacam (Oculus), Orbscan II (Bausch & Lomb), and WaveScan (Visx) in evaluating topographic features identified as risk factors for ectasia after laser in situ keratomileusis to identify parameters that may be important in interpreting elevation topography and wavefront data when screening refractive surgery candidates. SETTING: Private practice, New York, New York, USA. METHODS: One hundred forty‐five eyes of 75 consecutive patients were evaluated for refractive surgery by ultrasound pachymetry (Humphrey Atlas), videokeratography, WaveScan, Orbscan II, and Pentacam. Eyes were classified as normal or suspect based on the Rabinowitz criteria for keratoconus suspect on Placido disk‐based videokeratography. Forty‐six parameters were evaluated in a comparison of topographically normal eyes and eyes that met the criteria for keratoconus suspect. RESULTS: The suspect group had thinner pachymetry, multiple distinguishing characteristics on the anterior and posterior corneal surfaces by elevation topography, and larger amounts of coma by wavefront analysis. Multivariable regression analysis identified the following as the strongest predictors of a suspect Placido topography: Pentacam, thinner pachymetry and larger differences between the highest and lowest points on the posterior elevation; Orbscan II, higher anterior maximum elevation, horizontal location of the thinnest point on the pachymetry map, and larger differences between the highest and lowest points on the posterior elevation. CONCLUSION: Several parameters provided by the Pentacam, Orbscan II, WaveScan, and pachymetry were statistically correlated with keratoconus suspect, defined by higher asymmetry and steeper curvature on Placido topography.

Infectious keratitis after photorefractive keratectomy

PURPOSE To elucidate risk factors, microbial culture results, and visual outcomes for infectious keratitis after photorefractive keratectomy (PRK). DESIGN Multicenter, retrospective chart review, case report, and literature review. METHODS The records of 12 patients with infectious keratitis after PRK were reviewed. MAIN OUTCOME MEASURES Causative organism, response to medical treatment, and visual outcome. RESULTS Infectious keratitis developed in 13 eyes of 12 patients after PRK. Organisms cultured were Staphylococcus aureus (n = 5), including a bilateral case of methicillin-resistant Staphylococcus aureus; Staphylococcus epidermidis (n = 4); Streptococcus pneumoniae (n = 3); and Streptococcus viridans (n = 1). Four patients manipulated their contact lenses, and 2 patients were exposed to nosocomial organisms while working in a hospital environment. Prophylactic antibiotics used were tobramycin (nine cases), polymyxin B-trimethoprim (three cases), and ciprofloxacin (one case). Final best spectacle-corrected visual acuity ranged from 20/20 to 20/100. CONCLUSIONS Infectious corneal ulceration is a serious potential complication of PRK. Gram-positive organisms are the most common pathogens. Antibiotic prophylaxis should be broad spectrum and should include gram-positive coverage.

To lift or recut: Changing trends in LASIK enhancement

Purpose: To report serious complications caused by recutting laser in situ keratomileusis (LASIK) flaps for enhancement and reconsider the current preferred method of LASIK enhancement. Setting: Multiple surgeon practices. Methods: This retrospective noncomparative nonconsecutive case series comprised LASIK patients in the private practices of 9 experienced refractive surgeons and those reported in a survey of refractive surgeons. Case histories, refractions, corneal topographies, slitlamp photographs, and measurements of uncorrected and best corrected (BCVA) visual acuity after recutting LASIK flaps were collected. Surveys of refractive surgeons and an analysis of changing practice trends among the authors and these surgeons were assessed. Results: In 12 cases, significant loss of BCVA and subjective visual difficulties resulted from recutting LASIK flaps. Most surveyed surgeons had changed their practice from recutting to lifting flaps even 9 to 10 years postoperatively with good results. Conclusion: Recutting flaps for enhancement should be avoided unless other alternatives are unavailable.

Nocturnal Lagophthalmos: An Overview and Classification

Nocturnal lagophthalmos is the inability to close the eyelids during sleep. Lagophthalmos is associated with exposure keratopathy, poor sleep, and persistent exposure-related symptoms. There are a variety of causes of lagophthalmos, grouped as proptosis/eye exposure etiologies and palpebral insufficiency etiologies. Although obvious lagophthalmos is usually detected, it is sometimes difficult to recognize obscure lagophthalmos, due either to eyelash obstruction or overhang of the upper lid anterior and inferior to the most superior portion of the lower lid in a closed position. We present a novel classification system and illustrations of obvious and obscure lagophthalmos. A diagnosis can usually be made with a focused history and slit lamp examination. Treatment is multipronged and may include minor procedures or ocular surgery to correct the lid malposition; natural, topical or oral agents; and punctal plugs to manage ocular surface effects. Correct and timely diagnosis allows greater opportunity for relief of patient suffering and prevention of severe ocular surface pathology, as well as educated planning for future ocular surgical procedures.