Malcolm G. Kerr-Muir

Postoperative inflammatory response to phacoemulsification and extracapsular cataract surgery: Aqueous flare and cells

Purpose: To compare the postoperative blood‐aqueous barrier (BAB) breakdown induced by phacoemulsification with continuous curvilinear capsulorhexis (CCC) and by extracapsular cataract extraction (ECCE) with a linear capsulotomy. Setting: Cataract and Refractive Surgery Research Unit, Department of Ophthalmology, St. Thomas’ Hospital, London, United Kingdom. Methods: Anterior chamber flare and cells were measured preoperatively and 1 day, 1 week, and 1 and 3 months postoperatively in two parallel groups of 31 consecutive cataractous eyes. In Group 1, one surgeon performed ECCE with a linear capsulotomy; in Group 2, a second surgeon performed divide and conquer phacoemulsification with CCC. The preoperative, intraoperative, and postoperative medication regimen was the same in both groups. Results: Group 2 eyes had significantly lower anterior chamber flare and cell measurements in the first postoperative month than Group 1 eyes (.01 < P < .00001). Conclusions: Phacoemulsification with CCC induced a less severe BAB breakdown than ECCE with a linear capsulotomy. Phacoemulsification with CCC may be preferable in high‐risk eyes such as those with glaucoma, diabetes, or uveitis, which are prone to complications resulting from postoperative BAB breakdown.

The Effects of Topical Corticosteroids and Plasmin Inhibitors on Refractive Outcome, Haze, and Visual Performance after Photorefractive Keratectomy: A Prospective, Randomized, Observer-masked Study

BACKGROUND This study of 86 patients with 12 months of follow-up was designed to determine whether topical corticosteroids or plasmin inhibitors have an effect on the outcome of photorefractive keratectomy. METHODS Patients were allocated randomly to either steroid (0.1% fluorometholone for 6 months), plasmin-inhibitor (aprotinin 40 IU/ml for 3 weeks), or control (no treatment) groups and underwent either -3.00- or -6.00-diopter (D) corrections. RESULTS With -3.00-D corrections, the mean refractive change was significantly greater at 3 and 6 months (P < 0.05) in the steroid group compared with the control group. When steroids were discontinued, the difference became insignificant within 3 months. Similarly, with -6.00-D procedures the mean refractive change was greater at 6 weeks and 3 and 6 months (P < 0.01), but the refractive change again became insignificant 3 months after stopping steroid treatment. Four patients treated with steroids had a hyperopic shift greater than +2.00 D of that intended at 12 months. Similar overcorrections were not noted in the other treatment groups. There were no differences in refractive outcome between the aprotinin and control groups at any stage. With -6.00-D procedures, objective measurements of haze were significantly greater in the aprotinin group compared with the control group at 9 and 12 months (P < 0.05). With this exception, there were no differences in haze, forward or backward scatter of light, best-corrected visual acuity, or halo measurements between the groups. CONCLUSIONS Corticosteroids can maintain a hyperopic shift during their administration, but this effect is reversed on cessation of treatment. Objective tests have shown that steroids have no effect on corneal haze or visual performance after PRK. There is no justification for routinely submitting all patients to long-term steroid regimens and their associated side effects. Treatment with aprotinin produced no beneficial effect on refractive outcome, and haze was greater in the -6.00-D procedures. The concept of modulating the plasminogen activator/plasmin system to regulate wound healing after PRK is discussed.

Night vision after excimer laser photorefractive keratectomy: haze and halos

A series of 85 patients with myopia, up to −6.00D, was treated by photorefractive keratectomy (PRK), using a 5 mm diameter ablation zone. At six months, 38 patients (45%) reported slight disturbances of night vision, nine (11%) of whom had significant problems. Perturbations of night vision after PRK are seen as starbursts and halos around lights. Corneal haze produces the starbursts, which are usually transient. In contrast, halos are myopic blur circles and may be persistent. Using a computer program, halos after PRK were found to be significantly larger than those in emmetropes and myopes corrected with spectacles (p < 0.01). The halos were diminished by using either artificial pupils or negative lens over-correction. In patients with identical bilateral PRK corrections, except for the ablation zone size, the magnitude of the halo was less with 5 mm than 4 mm zones (p < 0.01). Patients treated with 5 mm reported fewer problems attributable to halo than with the 4 mm ablation diameters (p < 0.01). Halos and pupil diameters were measured in nine patients with significant impairment of night vision haze. Those with starbursts had small hyperopic shifts, minimal halos and high haze and light scatter measurements, whilst patients with halos had large hyperopic shifts, little haze and large pupil diameters. Patients with persistent halo problems benefited from either negative lens over-correction or miotics at night.

DISTURBANCES IN NIGHT VISION AFTER EXCIMER LASER PHOTOREFRACTIVE KERATECTOMY

Eighty-four patients with up to -6.00 dioptres of myopia underwent photorefractive keratectomy (PRK), using 5.00 mm ablation zones. Three months post-operatively 38 (45%) complained of disturbances in night vision, compared with 21 (25%) pre-operatively. In the majority, these disturbances were regarded as negligible. However, 9 (11%) reported significant problems, defined as an inability to drive safely at night with the treated eye. At 12 months, 32 patients (38%) complained of impaired night vision, 4 (5%) of whom had significant problems. A series of measurements were performed to investigate the origins of these disturbances, especially in patients reporting significant problems. Visual impairment from forward scattered light was investigated using a computerised technique. Back scattered light was measured with a charge coupled device–camera system and a computer program was used to assess the degree of halation around a bright light source on a high-resolution monitor. Pupillary diameters were measured by infrared television pupillometry. At 6 months, those reporting a starburst effect around lights at night had small hyperopic shifts, minimal halos and high forward and back light scatter measurements. Patients who reported halo phenomena had large hyperopic shifts, little light scatter and large pupillary diameters. Of the 4 patients who reported significant disturbances at 12 months, all had persistent halo problems. Those with starburst effects in the early postoperative period noticed an improvement with time as their corneal haze gradually improved. Perturbations of night vision after PRK manifest as starbursts and halos around lights. Disturbances in corneal transparency appear to be responsible for starburst effects and are usually transient. Halos are myopic blur circles and may be persistent in a small number of individuals. All patients should be informed pre-operatively of the possible consequences of disturbances in night vision.

Cellular reaction on the anterior surface of poly(methyl methacrylate) intraocularlenses

Purpose: To assess the cellular reaction on the anterior surface of poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) implanted by phacoemulsification with continuous curvilinear capsulorhexis (CCC) or by extracapsular cataract extraction (ECCE) with a linear capsulotomy. Setting: Cataract and Refractive Surgery Research Unit, Department of Ophthalmology, St. Thomas’ Hospital, London, United Kingdom. Methods: To document morphology, topography, and severity of the cellular reaction, specular microscopy of the anterior IOL surface was performed at 1 day, 1 week, and 1 and 3 months postoperatively in two parallel groups of 31 consecutive cataractous eyes operated on by phacoemulsification with CCC or by ECCE with a linear capsulotomy. Results: The local tissue response consisted of a nonspecific foreign‐body reaction to the IOL and a lens epithelial cell reaction. The foreign‐body reaction was significantly less severe in the phacoemulsification group than in the ECCE group, and the number of IOLs without inflammatory cells was significantly higher. Conclusion: The foreign‐body reaction to PMMA IOLs is significantly reduced when the lens is implanted by phacoemulsification with CCC. This could be of clinical benefit in high‐risk eyes prone to the inflammatory complications of cataract surgery.

Mycobacterium chelonei keratitis: a case report and review of previously reported cases

A 56-year-old woman who wore hard contact lenses developed a keratitis due to Mycobacterium chelonei. The organism was only sensitive to imipenem and partially to ciprofloxacin and erythromycin. After an initial response to topical therapy with these antibiotics the infection relapsed and a penetrating keratoplasty was performed, with resulting cure. M. chelonei has not previously been reported as a cause of keratitis associated with hard contact lens wear; neither has its treatment with imipenem and/or ciprofloxacin. A detailed photographic record showing the natural history of the keratitis is presented. Previously reported cases of M. chelonei keratitis are reviewed.

Discrimination between the origins and functional implications of haze and halo at night after photorefractive keratectomy.

A series of 84 eyes with up to -6.00 diopters (D) of myopia were treated by photorefractive keratectomy (PRK) using a 5.00 mm ablation zone. Three months postoperatively, 43 eyes (51%) complained of disturbed night vision, compared to 12 (14%) preoperatively. Ten (12%) had significant problems, ie, interference with driving at night. At 12 months, there were 32 patients (38%) with minor disturbances of night vision, 4 (5%) with significant problems.