Keratocyte density and size in conscious humans by digital image analysis of confocal images.

PURPOSE: Confocal microscopy can give images of high magnification and resolution in undisturbed living tissue. It provides new information about the cellular structure of the cornea. Our aim was to measure the density, size and distribution of keratocytes. METHODS: Healthy cornea in four subjects was examined using tandem scanning confocal microscopy. Methods for digital analysis of images were developed. RESULTS: Keratocyte density in confocal cross-sections was greatest immediately under Bowman's membrane (maximum 800 cells/mm2) and decreased sharply towards posterior cornea (minimum 65 cells/mm2). Cross-sectional cell size ranged from 78 to 211 microns2, but did not correlate with depth in the tissue. CONCLUSIONS: Results are consistent with those of earlier work using histological and biochemical techniques in isolated tissue. The methods we have developed enable studies of ongoing processes in conscious humans and can be used to examine diseased tissue as well as the response to injury.

Photorefractive keratectomy. A 6-year follow-up study.

OBJECTIVE: This study aimed to assess the long-term stability and efficacy of excimer laser photorefractive keratectomy. DESIGN: Patients who participated in the first United Kingdom photorefractive keratectomy clinical trial were asked to attend a 6-year follow-up assessment. PARTICIPANTS: Eighty-three patients (68%) of the original cohort of 120 participants were observed for 6 years. A Summit Technology UV200 excimer laser with a 4-mm ablation zone had been used with patients allocated to one of six groups according to their preoperative refraction. Each group received one of the following spherical corrections: -2, -3, -4, -5, -6, or -7 diopters (D). Within each group, all patients received an identical treatment, and thus emmetropia was not the goal in all patients. INTERVENTION: The induced refractive change, objective corneal haze, glare, and halo measurements, together with possible late-phase complications, were analyzed. MAIN OUTCOME MEASURES: All groups achieved a refractive undercorrection, and the magnitude of the undercorrection was related to the size of the attempted correction. The induced refraction stabilized by 6 to 12 months and has been maintained up to the 6-year follow-up stage. RESULTS: Ninety-one percent of patients who underwent a -2.00-D correction and 76% of patients who received a -3.00-D correction were within +/- 1 D of the intended refraction at 6 years. Fifty-seven percent of the -4.00-D group and 50% of those in the -5.00-D group were within +/- 1 D, and this was reduced further to 43% in the -6.00-D group and 19% in the -7.00-D group. Six patients (7%) had evidence of residual corneal haze, which was visually significant in two patients (3%). Ten patients (12%) had significant night halos due to the small 4-mm ablation zone that was used in this early treatment trial. CONCLUSIONS: There was no further regression of the refraction after 1 year, and, more important, there was no sign of hyperopic shift or diurnal fluctuation in the patients' refraction. In addition, corneal haze appeared to reduce further with time, with no intraocular or retinal side effects being noted. Night halos remain a significant reported problem in a small number of patients who were treated with the 4-mm ablation zone.

Confocal microscopy using oblique sections for measurement of corneal epithelial thickness in conscious humans.

PURPOSE: Thickness measurements by confocal microscopy in conscious human subjects may be liable to error as a result of instability of the eye or instrument. Our aim was to evaluate a technique which was expected to be less sensitive to such problems. METHOD: Thickness of corneal epithelium was determined from oblique confocal sections through cornea. A contact lens of known thickness worn by subjects was used to calibrate images. RESULTS: There were two layers in images which could have corresponded to the stromal/epithelial interface. The mean result in each subject ranged from 38 to 53 microm using the more superficial layer and 46 to 60 microm using the deeper one. The smaller values gave the distance between the epithelial surface and the sub-epithelial nerve plexus and thus seemed to correspond to epithelial thickness. CONCLUSIONS: Measurements of epithelial thickness by our new method are comparable with results of earlier studies.

Effects of ablation diameter, depth, and edge contour on the outcome of photorefractive keratectomy.

PURPOSE: To investigate the effects of the ablation diameter, depth, and edge contour on the outcome of excimer laser photorefractive keratectomy (PRK). METHODS: A prospective study was conducted in which 60 patients (60 eyes) were randomly allocated to 5.00-mm, 6.00-mm, or 5.00 to 6.00-mm multizone treatment groups. All eyes underwent a -6.00 diopter (D) correction using a Summit Omnimed excimer laser. RESULTS: In eyes treated with 6.00-mm diameter zones, the initial hyperopic shift was reduced, with significant differences at 1 and 4 weeks (p < 0.01). At 6 and 12 months, the refractive changes were closer to the intended correction with 6.00-mm diameters. The predictability of PRK was improved with 6.00-mm zones, with a significant reduction in variance of the refractive changes, at all stages postoperatively (p < 0.05 to p < 0.001). Objective measurements of haze were significantly less at 1, 3, and 6 months with 6.00-mm ablations (p < 0.05). There were no differences between the 5.00-mm and the 5.00- to 6.00-mm multizone groups. Computerized measurements of "night" halo were significantly smaller in the 6.00-mm treatment group at 1 week and 1 month (p < 0.05). At 12 months, two patients treated with 5.00-mm zones and three with the 5.00- to 6.00-mm multizone complained of severe night vision disturbances. No 6.00-mm eyes were similarly affected. CONCLUSIONS: Treatment with a 6.00-mm spherical ablation diameter produced less initial overcorrection, improved predictability, and was associated with a reduction in postoperative halos and night vision disturbances. Creating a superficial blend zone with a 5.00- to 6.00-mm multizone treatment had no beneficial effect on the outcome.

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.

Cellular reaction on the anterior surface of poly(methyl methacrylate) intraocular lenses.

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.

The effects of ablation diameter on the outcome of excimer laser photorefractive keratectomy. A prospective, randomized, double-blind study.

OBJECTIVE: To determine the effects of the ablation diameter on the outcome of excimer laser photorefractive keratectomy. DESIGN: Eighty patients were randomized to either a 5.00-mm or a 6.00-mm treatment group and within these groups underwent either a -3.00-diopter (D) or a -6.00-D correction based on their preoperative refraction. A Summit Omnimed excimer laser was used throughout the study. RESULTS: In eyes treated with a 6.00-mm-diameter ablation, the initial hyperopic shift was reduced, with significant differences at 1 week with -3.00-D corrections and at 1 and 4 weeks with -6.00-D corrections (P < .01). At 6 months, the refractive changes were greater and closer to that intended with 6.00-mm-diameter ablations. The predictability of photorefractive keratectomy was significantly improved with 6.00-mm zones, with a reduction in variance of the refractive changes at all stages postoperatively (P < .05 to P < .001). With -3.00-D corrections, objective measurements showed significantly less anterior stromal haze in eyes treated with 6.00-mm zones at 6 months (P < .05). With -6.00-D corrections, haze was significantly reduced at 1, 3, and 6 months in the eyes treated with 6.00-mm zones (P < .05). Five eyes treated with 5.00-mm zones experienced severe regression of the correction, with marked corneal haze and a reduction of 3 or more lines of best corrected Snellen visual acuity at 6 months. No eyes treated with 6.00-mm zones were similarly affected. Computerized measurements of "night" halo were significantly lower in the 6.00-mm treatment groups at 1 week and at 1 and 6 months in the eyes with -3.00-D corrections and at 1 week and at 1 month in the eyes with -6.00-D corrections (P < .05). At 6 months, seven patients treated with 5.00-mm zones complained of severe disturbances of night vision. No eyes in the 6.00-mm group were similarly affected. CONCLUSIONS: Treatment with 6.00-mm ablation diameters precipitated less initial overcorrection, greatly improved the predictability of photorefractive keratectomy, and was associated with a reduction in complications impairing postoperative visual performance.

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.

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.

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.

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.

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 post-operative 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of band keratopathy by excimer laser phototherapeutic keratectomy: surgical techniques and long term follow up.

A series of 122 eyes with band keratopathy was treated by excimer laser phototherapeutic keratectomy (PTK), with a mean follow up of over 12.3 months (range 3 to 60 months). A single photoablation zone was used to remove the opacity over the visual axis in smooth surfaced band deposition. In eyes with reduced vision, an improvement was reported in 88% and in a series of 66 eyes mean Snellen visual acuity increased significantly (p < 0.05, t = 2.27). A reduction in glare was reported in 88% and in a series of 17 patients, visual contrast sensitivity (p < 0.01) and measurements of disability glare (p < 0.01) improved postoperatively. The mean hyperopic shift in 32 eyes at 6 months was 1.4 D (range 0-4.25 D). Multiple overlapping ablation zones, with mechanical debulking of large calcium plaques, were used to smooth the irregular corneal surface in eyes with rough bands. Ocular discomfort was improved in 95%. Band keratopathy recurred in nine eyes (8%) within 2 to 30 months (mean 12 months) of surgery, with silicone oil responsible in five eyes. Reablation was necessary in three eyes and performed successfully in all cases. Excimer laser PTK is a safe and effective outpatient treatment for band keratopathy.

Primary low-grade B-cell lymphoma of the conjunctiva: a mucosa-associated lymphoid tissue type lymphoma.

We describe the clinical presentation, morphology, immunophenotypic features and molecular biology of seven cases of conjunctival lymphoid infiltration. In five cases there was either immunophenotypic or molecular evidence of B-cell lymphoma. Each of these cases showed the morphological, immunophenotypic and molecular feature of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. The findings suggest that most conjunctival lymphomas are of this type and explains their uniformly favourable prognosis.

Excimer laser photorefractive keratectomy. 18-month follow-up.

PURPOSE: This study, comprising 120 patients (follow-up, 12 to 22 months; mean, 18 months), was designed to evaluate the efficacy and safety of excimer laser photo-refractive keratectomy. METHODS: Ablation zone diameter (4 mm), ablation rate (0.22 microns/pulse), fluence (180 mJ/cm2), and frequency (10 Hz) were kept constant, and all patients used a standard topical corticosteroid regimen. RESULTS: Overcorrection was followed by regression to a stable refraction by 4 months. At 1 year, 95% and 70%, respectively, of patients undergoing - 2.00 diopters (D) and -3.00 D corrections and 40% and 20% of those undergoing -6.00 D and -7.00 D corrections were within +/- 1.00 D of intended refraction. Anterior stromal "haze," maximal at 6 months and diminishing thereafter, was detected in 110 patients (92%). However, best-corrected Snellen visual acuity was reduced in only 22 (18%). Good correlation existed between haze and regression (r = 0.68). Night "halos," due to the relatively small 4-mm diameter ablation zone, were reported by 94 patients (78%) in the early postoperative period, and, at 1 year, 12 (10%) declined treatment of the other eye because of persistence of this problem. CONCLUSION: Marked individual variation was found after photorefractive keratectomy. However, in low myopia, predictability is "fair," and the procedure is safe. The authors conclude that excimer laser photorefractive keratectomy holds considerable promise for refractive surgery in the future.

Sclerocornea and interstitial deletion of the short arm of chromosome 6--(46XY del[6] [p22 p24]).

The interstitial deletion of the short arm of chromosome (6)--46 XY del (6) (p22.3 p24) is unrecorded. The ophthalmic findings in a dysmorphic infant included peripheral sclerocornea and epicanthal folds with upslanting palpebral fissures. We present a short review of sclerocornea and the ophthalmic findings of infants with anomalies of chromosome 6. Our findings provide further evidence that genes influencing the development of the anterior segment are located on the distal portion of the short arm of chromosome 6.

Glaucoma and the iridocorneal endothelial syndrome.

The records of 66 patients with the iridocorneal endothelial (ICE) syndrome were retrospectively reviewed. Glaucoma occurred in 33 (50%) of the patients with ICE syndrome and was most common in the variants in which abnormal cells involve the entire posterior corneal surface (disseminated ICE and total ICE). Of 25 patients with glaucoma, the diagnosis of ICE syndrome was overlooked initially in 17 (68%). Medical glaucoma treatment was generally ineffective. Of 22 patients (88%) who underwent surgery (typically trabeculectomy), 10 (45%) required more than one procedure. The success rates of first operations at 1 and 5 years were 60% and 21%, and those of second and third operations at 1 year were 20% and 17%. During the course of their management, 11 patients (44%) developed visual field loss. The diagnosis of ICE syndrome should be considered in younger patients with unilateral glaucoma and confirmed by specular microscopy. Management of glaucoma due to ICE syndrome is surgical, and means of improving its long-term success need to be addressed.

Photorefractive keratectomy with an argon fluoride excimer laser: a clinical study.

The results of excimer laser photorefractive keratectomy (PRK) in 16 blind and 120 sighted eyes (136 patients) are presented. Follow up for the blind eyes was 22 months and for the sighted eyes 8 to 18 months (mean, 1 year). A Summit Technology UV200 excimer laser with fluence fixed at 180 mJ/cm2, beam diameter 4 mm, a frequency of 10 Hz, and ablation rate of 0.22 mu per pulse was used. The range of preoperative myopia was - 1.50 diopters to - 17.50 D (spherical equivalent). Ninety percent of patients undergoing a -2.00 D correction and 75% of patients undergoing a -3.00-diopter correction were within +/- 1.00 D of intended refraction at 6 months. This figure fell to 40% and 20% for the groups undergoing -6.00 D and -7.00 D corrections, respectively. While the trend is toward undercorrection, around 70% of patients in all groups have benefited from a reduction of their myopia by at least half that intended. A variable degree of anterior stromal "haze" was detected in 110 patients (92%) despite a rigid high dose topical corticosteroid regime over 3 months. Best spectacle corrected visual acuity, however, was greater than or equal to preoperative levels in 111 patients (93%). Six patients experienced a reduction of one line of Snellen acuity at 6 months and three of the high myopes lost two lines. No patients lost more than two lines of Snellen acuity. Ninety-four patients (78%) noticed a "halo" around lights at night, more marked in the early postoperative period, which we attribute to the 4-millimeter diameter ablation zone. With a large pupil, both central and paracentral cornea can contribute simultaneously to the retinal image. We have demonstrated considerable individual variation in response to this surgery, which is more marked in high myopia. Although follow up at the present time is limited, to date PRK appears to be a safe procedure that holds considerable promise for refractive surgery in the future.