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.

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.

Ultrastructural comparison of conventional surgical and argon fluoride excimer laser keratectomy.

We used scanning electron microscopy to examine the structure of the surfaces created during keratectomy procedures carried out by conventional surgery and ablation by an excimer laser. The walls and the floor of the surgical site were rough with undulations greater than 10 micron in size, caused by broken lamellae and ruptured cells. In contrast, the surfaces produced by the excimer laser were smooth with perturbations of 1 micron or less and were sealed with a pseudomembrane. This smooth, sealed surface produced by the laser is probably responsible for the transparency of the healed cornea in contrast to the scarring produced when a conventional surgical keratotomy heals.

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.

Damage to the corneal endothelium during Nd/YAG photodisruption.

Damage to the human corneal endothelium, as seen by specular microscopy, associated with short pulsed neodymium: yttrium-aluminium-garnet (Nd/YAG) laser iridotomy and capsulotomy, is described. A specular and scanning electron microscopical study of fresh in vitro rabbit eyes submitted to Nd/YAG iridotomy was performed to investigate the nature of the endothelial damage. The majority of lesions showed irreversible changes ranging from individual cell destruction to disruption of large areas of the endothelium, while cells adjacent to these lesions had changes of an apparently reversible nature. It was possible to correlate accurately these scanning electron microscopic changes with the appearances seen with the clinical specular microscope. The extent of such damage appears to be related to the quantity of power delivered, its delivery mode, the number of laser bursts, and the target tissue/endothelium distance. The possible causes for such damage are discussed.

Postoperative grey-white lines of the posterior cornea and endothelial cell damage.

'Snailtracks' (grey-white streaks and patches on the posterior corneal surface which occur postoperatively) have recently been implicated as possible markers of corneal endothelial cell damage. We have examined this phenomenon in vivo with the slit-lamp and specular microscope. We recognised three types of linear form and, in contradiction of other observers, found that each was always coincident with a wrinkle in Descemet's membrane. Moreover, we were able to demonstrate only minimal endothelial cell damage in only a few of the tracks.

Corneal thickness, astigmatism, and atopy.

Keratometry and regional pachometry were performed on atopic patients with no history or signs of atopic keratoconjunctivitis. In a series of 80 eyes there was a skewed distribution towards thinner corneas (p less than 0.01) and a preponderance of against-the-rule astigmatism. The maternal age at birth of this group of patients was higher than that in the general population. These findings are discussed in the context of the known association of atopy with keratoconus.

Ocular hypertension and posture.

Thirty-seven patients with ocular hypertension (OH) and 29 age matched controls were studied. Intraocular pressure (IOP) measurements were made in the sitting position and, immediately after changing posture, in the lying position. Sixty-three (85%) of the OH eyes and all the control eyes showed either stable IOP readings on changing posture of small elevations up to 3 mmHg. Eleven (15%) of the OH eyes showed larger elevations of IOP, between 5 and 9 mmHg when the patients changed to the lying position. We suggest that an IOP measurement in the lying position should be included in the routine evaluation of the patient with ocular hypertension.

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.

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.

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.

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.

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.

Damage to the corneal endothelium by Q-switched Nd:YAG laser posterior capsulotomy.

Clinical specular microscopy of the corneal endothelium of eyes immediately before and after Nd:YAG laser posterior capsulotomy revealed apparent endothelial damage. Comparative specular and scanning electron microscopical studies in rabbits showed extensive cell destruction, and clinical observations indicated 'healing' of the lesions by extensions from neighbouring cells. Possible causes of the damage are discussed.