Effect of lodoxamide and disodium cromoglycate on tear eosinophil cationic protein in vernal keratoconjunctivitis

AIM—To validate the use of tear eosinophil cationic protein (ECP) as a marker for eosinophil activation, and its pharmacological modulation, in addition to evaluating the efficacy of lodoxamide and sodium cromoglycate in the treatment of vernal keratoconjunctivitis (VKC).
METHODS—Tears were collected from 30 patients affected by active mild to moderate VKC before and after therapy with disodium cromoglycate 4% (DSCG) (n=15) or lodoxamide 0.1% (n=15) for 10 days. Tear cytology and ECP measurement were performed, and ocular signs and symptoms evaluated.
RESULTS—While statistically significant changes did not occur after DSCG therapy, mean tear ECP increased from 343 (SD 363) µg/l to 571 (777) µg/l due to marked elevation in six eyes. The clinical score in DSCG eyes did not improve. After lodoxamide therapy, both clinical signs and symptoms, and tear ECP levels (560 (756) µg/l to 241 (376) µg/l) decreased significantly (p<0.0001 and p<0.01, respectively). Compared with DSCG treatment, lodoxamide was more effective in reducing signs and symptoms (p<0.005). ECP levels were significantly correlated with signs, symptoms, corneal involvement, and number of eosinophils in tears (p<0.0001).
CONCLUSIONS—In patients with VKC, lodoxamide significantly reduced ECP tear levels, and thus, eosinophil activation, and was more effective than DSCG in reducing clinical signs and symptoms.

     

Prospective study of New Zealand infants with birth weight less than 1500 g and screened for retinopathy of prematurity: visual outcome at age 7-8 years

AIM—To determine the visual outcome at 7-8 years in very low birth weight (VLBW: birth weight <1500 g) infants screened for retinopathy of prematurity (ROP).
METHODS—In 1986 all 413 VLBW infants admitted to neonatal units in New Zealand were enrolled in a prospective study of acute ROP. Surviving infants were traced and assessed at a home visit. Visual assessment comprised examination for abnormal and range of eye movements, visual fields, distance and near visual acuity, stereopsis, and photorefraction.
RESULTS—Of 338 infants surviving to discharge, 313 (93%) had been examined for acute ROP. ROP was present in 66 (21%: ROP+), absent in 247 (ROP−), with 25 not examined (NA). 298 children (96% survivors resident in New Zealand: 91% all survivors) were assessed. Any visual problem occurred in 79% ROP+ and 60% ROP−/NA (p<0.01). Distance visual acuity less than 4/10 in the worse eye occurred in 29% ROP+ and 15% ROP−/NA (p<0.05); and in the better eye in 19% ROP+ and 5% ROP−/NA (p<0.001). Any myopia in the worse eye occurred in 36% ROP+ and 18% ROP−/NA (p<0.01); and in the better eye in 25% ROP+ and 11% ROP−/NA (p<0.01). Strabismus, including treated, occurred in 33% ROP+ and 19% ROP−/NA (p<0.05). Overall, 11% had astigmatism and 18% hypermetropia with no difference between the groups.
CONCLUSION—In a population based study it was confirmed that VLBW is associated with an increased risk of visual problems at school age. A history of ROP is associated with an additional risk of poor outcome, including a near doubling of poor distance acuity, myopia, and strabismus.

     

Effects of latanoprost and dipivefrin, alone or combined, on intraocular pressure and on blood-aqueous barrier permeability

AIM—To investigate the effect on intraocular pressure (IOP) and aqueous flare of topical applications of latanoprost and dipivefrin alone or combined.
METHODS—22 patients with open angle glaucoma or ocular hypertension were included in a 4 week open label study. Median age was 68 years (range 50-79). They were allocated to either 2 weeks' treatment with once daily evening administration of latanoprost monotherapy (50 µg/ml) or twice daily dipivefrin monotherapy (1 mg/ml), followed by 2 weeks' combination therapy with both drugs.
RESULTS—Latanoprost alone reduced IOP from 19.3 (SD 1.4) to 14.8 (0.9) mm Hg (p<0.01). Addition of dipivefrin caused a further reduction to 12.4 (0.9) mm Hg (p<0.01 compared with latanoprost alone). In the group where the treatment started with dipivefrin IOP was reduced from 22.3 (1.2) to 18.4 (1.0) mm Hg (p<0.01) and with the combination to 14.9 (0.9) mm Hg (p<0.01). No change in aqueous flare was observed with either drug, alone or in combination. A slight increase in conjunctival hyperaemia was observed when the two drugs were combined.
CONCLUSIONS—Latanoprost and dipivefrin have an additive effect on IOP and no clinically significant effect on the permeability to proteins of the blood-aqueous barrier. This implies that the two drugs can be a useful combination for the treatment of glaucoma.

Keywords: aqueous flare; intraocular pressure; latanoprost; dipivefrin     

Partial reversal of protan and tritan colour defects with inhaled oxygen in insulin dependent diabetic subjects

AIMS—Abnormalities in colour perception occur early in the development of diabetic retinopathy. Whether these changes can be influenced by increasing circulating oxygen saturation was studied in comparison with non-diabetic controls.
METHODS—Protan and tritan colour thresholds were measured using a computer graphics system in 37 insulin dependent diabetic subjects, with no or minimal background retinopathy, and 27 matched controls. Colour thresholds were performed after subjects inhaled either gaseous air or 100% oxygen for a minimum of 5 minutes.
RESULTS—Diabetic subjects had higher colour vision thresholds when inhaling air when compared with controls (protan (mean 3.93 (SEM 0.39), v 2.36 (0.16), p<0.0002) and tritan (8.15 (0.62) v 5.42 (0.31), p <0.002)). The colour vision thresholds observed in diabetic subjects inhaling air fell when they inhaled oxygen (protan (3.93 (0.39) v 3.57 (0.33), p <0.025) and tritan (8.15 (0.62) v 7.35 (0.59), p<0.005)). No fall in colour thresholds was seen in non-diabetic controls who inhaled oxygen.
CONCLUSION—A small improvement in the colour vision thresholds was observed using computer graphics in diabetic subjects, with minimal or no retinopathy, who inhaled oxygen. This study supports a hypothesis that reduced retinal oxygenation contributes to the colour vision defects in diabetes.

     

Early detection of visual field progression in glaucoma: a comparison of PROGRESSOR and STATPAC 2

AIM—To compare the performance of PROGRESSOR (pointwise linear regression) and STATPAC 2 (comparison with baseline values) in detecting early deterioration in the visual fields of glaucoma patients.
METHODS—Visual field series from 19 untreated normal tension glaucoma eyes which were deteriorating on clinical grounds were analysed by PROGRESSOR and STATPAC 2. Progression criteria for PROGRESSOR were (1) inner points: slope < −1 dB/year, p < 0.05 and (2) edge points: slope < −2 dB/year, p < 0.05. Criteria for STATPAC 2 were p < 0.05 change probability for any point on three consecutive fields. Detection time was defined as the time interval between the initial field and the first field in which at least one progressing point was identified. Detection times produced by the two techniques were compared.
RESULTS—PROGRESSOR and STATPAC 2 agreed on progression in all 19 eyes. Mean detection time for PROGRESSOR was 1.077 (SD 0.985) years and for STATPAC 2 was 2.161 (1.357) years. PROGRESSOR detected progression sooner than STATPAC 2 in 18 eyes (p < 0.01, Wilcoxon matched pairs signed rank test). PROGRESSOR detected progression earlier by a mean of 1.085 (0.936) years.
CONCLUSIONS—PROGRESSOR consistently detected progression earlier than STATPAC 2. The PROGRESSOR software is a useful tool for the early detection of visual field deterioration in glaucoma.

     

Retinopathy of prematurity screening, stress related responses, the role of nesting

AIMS/BACKGROUND—In a prospective study the degree of distress caused by retinopathy of prematurity (ROP) screening in a cohort of preterm infants was assessed and the modifying effects of nesting in reducing their discomfort was evaluated.
METHODS—38 preterm infants were included in the study. 19 infants were placed in a nest with boundaries (intervention group) and 19 infants were placed on a cot blanket (control group). Observations were made 2 minutes before, throughout, and 2 minutes after ROP examination. The factors observed were crying responses, neurobehavioural activity, and physiological changes (heart rate, oxygen saturation). Recordings were made using a video camera for crying and neurobehavioural activity and an Oxypleth monitor for heart rate and oxygen saturation.
RESULTS—During ROP screening, the total group of 38 infants (nested and non-nested combined) displayed increased neurobehavioural activity (p<0.01) and crying (p<0.01). The increased activity and crying coincided with the invasive part of the procedure. The distress caused by ROP screening was significantly less for the nested group compared with the non-nested group for both movement activity (p<0.01) and crying (p<0.01). The physiological data, heart rate, and oxygen saturation were not statistically significant.
CONCLUSION—ROP screening is distressing for preterm infants. Nesting can significantly reduce this discomfort. The findings in this study are of value in designing more optimal ROP examination schedules for infants.

     

Evidence that upregulation of serum IGF-1 concentration can trigger acceleration of diabetic retinopathy

BACKGROUND—Acute reduction of chronic hyperglycaemia can accelerate early diabetic retinopathy. In adolescent patients with Mauriac's syndrome, this phenomenon is related to an upregulation of subnormal serum IGF-1 levels.
AIM—To obtain longitudinal data on serum IGF-1 and retinopathy status in poorly controlled adult insulin dependent (type 1) diabetic patients without Mauriac's syndrome, in whom hyperglycaemia is reduced by intensive insulin therapy.
METHODS—Four patients with chronic severe insulin deficiency and early microangiopathy were studied prospectively. Changes in plasma glucose, HbA_1c, serum IGF-1 levels, proteinuria, retinopathy, and clinical status were followed up closely.
RESULTS—Reducing hyperglycaemia from >16 mmol/l (equivalent to HbA_1c >11%) to <10 mmol/l (HbA_1c <8%) within 5 months increased serum IGF-1 levels by 70-220%. While proteinuria and symptomatic neuropathy regressed, retinopathy progressed from the mild to the severe non-proliferative stage with maculopathy (n=4), and to the proliferative stage (n=1). Laser coagulation was commenced upon the appearance of sight threatening macular oedema (n=4).
CONCLUSION—Upregulation of serum IGF-1 preceding retinal deterioration in these patients suggests a cause-effect relation, consistent with earlier experimental and clinical data.

Keywords: diabetes mellitus; macular oedema; metabolic control; intensive therapy; glycated haemoglobin A_1c; growth factors     

Orbital fibroblast chemokine modulation: effects of dexamethasone and cyclosporin A

AIM—Orbital inflammation is common, but the mechanisms underlying leucocytic infiltration of orbital tissue are poorly understood. Human orbital fibroblasts (OF) express chemokines, interleukin 8 (IL-8) and monocyte chemotactic protein 1 (MCP-1), when exposed to proinflammatory cytokines. The effects of dexamethasone (DEX) and cyclosporin A (CSA) on OF IL-8 and MCP-1 were examined.
METHODS—Cultured human OF were incubated with recombinant interleukin 1β (rIL-1β; 0.2, 2.0, 20 ng/ml) alone or incubated with rIL-1β and DEX (10^-8, 10^-7, 10^-6 M) or CSA (3, 30, 300 ng/ml) for 24 hours. ELISA and northern blot analyses were performed to determine OF IL-8 and MCP-1 protein secretion and mRNA expression, respectively.
RESULTS—OF lacked constitutive IL-8 or MCP-1 expression, but secreted significant amounts of these chemokines and expressed substantial steady state mRNA for both chemokines upon rIL-1β stimulation. DEX caused dose dependent inhibition of IL-1 induced IL-8 (p<0.001) and MCP-1 (p<0.05) secretion and mRNA expression at all concentrations of rIL-1β. CSA enhanced IL-1 induced OF IL-8 (p<0.001) and suppressed rIL-1β induced OF MCP-1 (p<0.05) secretion when lower doses of rIL-1β were used. These effects on secreted chemokines at different concentrations of rIL-1β and immunomodulating agents were corroborated by steady state OF IL-8 and MCP-1 mRNA expression.
CONCLUSIONS—DEX is a potent inhibitor of OF IL-8 and MCP-1. In contrast, CSA enhances IL-1 induced OF IL-8 and suppresses OF MCP-1. These observations may explain the relative lack of CSA effectiveness in human orbital diseases that respond to corticosteroids.

Keywords: orbital fibroblasts; chemokines; dexamethasone; cyclosporin A     

Plasma endothelin-1 concentrations in patients with retinal vein occlusions

AIMS—To investigate whether plasma levels of endothelin-1 (ET-1), a potent vasoconstricting peptide that is crucial in regulating retinal blood flow, were elevated in patients with retinal vein occlusion (RVO).
METHODS—ET-1 plasma concentrations were determined by radioimmunoassays in a double blind fashion in a group of 18 selected patients with RVO, in 20 healthy age matched non-smoking, normoglycaemic, normotensive control subjects, and in 15 patients with uncomplicated essential hypertension in the same age range.
RESULTS—Patients with RVO had significantly increased ET-1 plasma levels (14.22 (SD 4.6) pg/ml) compared with both normal subjects (7.90 (1.6) pg/ml; p < 0.05) and hypertensive patients (8.50 (2.9) pg/ml; p <0.05). The highest concentrations of circulating ET-1 were found in patients with RVO of the ischaemic type (16.97 (3.5) pg/ml; p < 0.01; n = 7). Systemic hypertension alone did not account for the observed increase in plasma ET-1 concentrations.
CONCLUSIONS—These findings raise the possibility that the increased circulating ET-1 levels in patients with RVO may be a marker of the occlusive event, thereby suggesting that ET-1 homeostasis may be relevant to RVO pathogenesis and retinal ischaemic manifestations.

Keywords: endothelin-1; hypoxia; ischaemia; retinal vein occlusion; thrombogenesis; venous stasis     

Variation in indications for cataract surgery in the United States, Denmark, Canada, and Spain: results from the International Cataract Surgery Outcomes Study

BACKGROUND/AIMS—International comparisons of clinical practice may help in assessing the magnitude and possible causes of variation in cross national healthcare utilisation. With this aim, the indications for cataract surgery in the United States, Denmark, the province of Manitoba (Canada), and the city of Barcelona (Spain) were compared.
METHODS—In a prospective multicentre study, patients scheduled for first eye cataract surgery and aged 50 years or older were enrolled consecutively. From the United States 766 patients were enrolled; from Denmark 291; from Manitoba 152; and from Barcelona 200. Indication for surgery was measured as preoperative visual status of patients enlisted for cataract surgery. Main variables were preoperative visual acuity in operative eye, the VF-14 score (an index of functional impairment in patients with cataract) and ocular comorbidity.
RESULTS—Mean visual acuity were 0.23 (USA), 0.17 (Denmark), 0.15 (Manitoba), and 0.07 (Barcelona) (p<0.001). When restricting the sample to eyes with normal retina and macula, no significant difference between United States and Denmark was observed (p>0.05). Mean VF-14 scores were 76 (USA), 76 (Denmark), 71 (Manitoba), and 64 (Barcelona) (p<0.001).
CONCLUSION—Similar indications for cataract surgery were found in the United States and Denmark. Significantly more restricted indications were observed in Manitoba and Barcelona. Possible explanations for the results are discussed, including differences in sociodemographic characteristics, access to care, surgeons' willingness to operate, and patient demand.

Keywords: cataract surgery; North America; Europe     

Increased release of tumour necrosis factor-α in human tear fluid after excimer laser induced corneal wound

AIMS—To measure the pre- and postoperative tear fluid tumour necrosis factor-α (TNF-α) concentration and release in patients undergoing excimer laser photorefractive keratectomy (PRK).
METHODS—Tear fluid samples from 18 PRK patients were collected with scaled microcapillary tubes preoperatively (day 0), on the second (day 2), and on the seventh (day 7) postoperative days. The TNF-α concentration was measured using a double antibody radioimmunoassay, and the TNF-α release was calculated by multiplying the concentration by the tear fluid flow in the collection capillary.
RESULTS—The mean tear fluid flow in the capillary was 22.5 µl/min (range 1.5-93.2) on day 0, 80.7 µl/min (3.0-219, p = 0.0002) on day 2, and 14.6 µl/min (1.8-41.7, NS) on day 7. The mean TNF-α concentration and release values were: day 0, 358 ng/l (110-680) and 9.5 pg/min (0.2-37.5, NS); day 2, 417 ng/l (< 5-750, NS) and 28.6 pg/min (0.6-81.5; p = 0.003); and day 7, 320 ng/l (< 5-735, NS) and 4.8 pg/min (0-25.4, NS), respectively.
CONCLUSION—TNF-α appears to be a component of normal tear fluid. In spite of hypersecretion caused by the corneal wound, TNF-α concentrations remain constant during wound healing. TNF-α release increases significantly during the 2 postoperative days following PRK, suggesting a role in corneal wound healing.

     

Vitreous intercellular adhesion molecule 1 in uveitis complicated by retinal detachment

AIMS—The vitreous levels of soluble intercellular adhesion molecule 1 (sICAM-1) were investigated in uveitic eyes undergoing vitrectomy for retinal detachment (RD) or other complications, and the presence of this molecule was related to disease activity and vitreous levels of the cytokine tumour necrosis factor α (TNFα), known to upregulate ICAM-1 expression on various cells.
METHODS—Vitreous and serum samples from 23 patients with either active or quiescent uveitis undergoing retinal surgery were examined for the levels of immunoreactive sICAM-1 and TNFα by ELISA methods, and for the presence of biologically active TNFα. Vitreous from non-uveitic eyes with rhegmatogenous retinal detachment (RRD), macular holes or cadaveric eyes were used as controls.
RESULTS—As a whole, vitreous from uveitic eyes complicated or uncomplicated by RRD contained significantly higher levels of sICAM-1 than vitreous from non-uveitic eyes with RRD alone (p < 0.0005), eyes with macular holes (p< 0.0001), or normal cadaveric vitreous (p < 0.0001). The proportion of vitreous containing >20 ng/ml sICAM-1 (> four times the normal values) was significantly higher in eyes with uveitis complicated by RRD than in those eyes without RRD (Fisher's test, p= 0.02), and although levels of sICAM-1 were higher in eyes with active uveitis than in those with quiet disease (p < 0.02), this could not be dissociated from the increase caused by RRD. There was a relation between the vitreous levels of sICAM-1 and those of immunoreactive TNFα (Spearman's correlation coefficient; r = 0.601, p = 0.006), but not between the vitreous levels of sICAM-1 and those of biologically active TNFα.
CONCLUSION—Increased vitreous sICAM-1 levels and the association of this molecule with the presence of immunoreactive TNFα in uveitic eyes confirm the operation of cytokine mediated vascular reactions at the blood-retinal barrier during the development of this condition. The persistence of high vitreous levels of sICAM-1 in eyes with uveitis complicated by RRD despite previous immunosuppression may indicate a low rate of clearance of inflammatory molecules from the vitreous cavity and an exacerbation of the existing inflammatory process by the retinal detachment itself.

Keywords: vitreous; retinal detachment; ICAM-1; TNFα; uveitis     

Pseudoexfoliation syndrome and secondary cataract

AIM/BACKGROUND—The pseudoexfoliation (PEX) syndrome is frequently associated with impairment of the blood-aqueous barrier. This study analysed if this might stimulate secondary cataract following cataract extraction.
METHODS—This historical cohort study included 197 eyes of 197 patients (99 with and 98 without PEX) that underwent extracapsular cataract extraction with posterior chamber lens implantation (PMMA optic) between 1985 and 1991. Secondary cataract was defined as opacification of the axial posterior capsule and decrease of visual acuity by two or more lines. Mean follow up was 23.8 months. For statistical analysis, the Kaplan-Meier method and multivariate Cox regression analysis were used.
RESULTS—Secondary cataract was observed within 24 months in 35% (SD 7%) of all eyes, and was significantly more frequent in eyes with PEX (45 (11)%) than in eyes without PEX (24 (9)%, p<0.03). Eyes with diabetes mellitus (n=32) showed a significantly lower frequency of secondary cataract (11 (11)%) than eyes without diabetes mellitus (39 (8)%, p<0.01). The influences of sex, open angle glaucoma, type of cataract, surgeon, positioning of IOL, and phacoemulsification versus nuclear expression on secondary cataract did not reach statistical significance.
CONCLUSION—The higher frequency of secondary cataract could be considered as another potential complication of cataract surgery in eyes with PEX.

     

CA 19-9 ELISA test: a new method for studying mucus changes in tears

AIMS—This study investigated mucus changes in the tears in various eye conditions using impression cytology. The quantity of mucins was measured by enzyme linked immunosorbent assay (ELISA) using the tumour marker CA 19-9. This assay quantifies the sialylated Lewis^a structure mainly associated with ocular mucins.
METHODS—Impression cytology was performed using a cellulose nitrate membrane, on 53 healthy patients, 50 glaucoma patients treated with β blockers, 24 patients suffering from dry eye syndrome, and 45 contact lens wearers. The tear film glycoproteins were eluted and CA 19-9 was measured.
RESULTS—CA 19-9 content expressed as kilo units (kU) per µg of tears was significantly decreased in dry eye syndrome (25.8 kU (SD 17.3)/µg) (p<0.05), glaucoma patients over 60 years (28.9 (19.5) kU/µg) (p<0.05), and contact lens wearers (28.4 kU (18)/µg) (p<0.05), when compared with healthy individuals (39.4 kU (22.2)/µg).
CONCLUSION—Impression cytology can be regarded as a valuable method for obtaining samples of glycoconjugates of mucin. The decrease of sialylated chains observed with this method confirms the hypothesis that some quantitative changes in the tear film may be encountered in ocular surface disorders.

Keywords: impression cytology; tears; glycoconjugate; sialic acid     

Neuroretinal rim width ratios in morphological glaucoma diagnosis

AIMS—To evaluate the inferior to temporal neuroretinal rim width ratio and superior to temporal rim width ratio as measures of rim shape for diagnosis of glaucoma.
METHODS—Colour stereo optic disc photographs of 527 normal subjects, 100 ocular hypertensive individuals with normal visual fields, and 202 open angle glaucoma patients with a mean perimetric defect of less than 10 dB were morphometrically evaluated. Eyes with an optic cup area of < 0.2 mm² were excluded.
RESULTS—In the normal subjects, inferior to temporal rim width ratio (1.67 (SD 0.53)) was significantly (p<0.0001) higher than superior to temporal rim width ratio (1.56 (0.49)). Both ratios were significantly (p<0.0001) higher the more vertically the optic disc was configured. In the normal eyes, both ratios were statistically independent of disc size, rim area, refractive error, age, and sex. With the differences being more marked for the inferior to temporal ratio than for the superior to temporal ratio, both rim width ratios were significantly (p<0.005) lower in the ocular hypertensive group than in the normal group. Despite the high significance of the differences, diagnostic power of the inferior ratio and the superior ratio was 59% and 58%, respectively, indicating a marked overlap between the groups.
CONCLUSIONS—Abnormally low inferior to temporal and superior to temporal rim width ratios can indicate glaucomatous optic nerve damage in some ocular hypertensive eyes. Being independent of optic disc size and ocular magnification, the rim width ratios may be taken as one among other variables for the ophthalmoscopic optic disc evaluation, taking into account, however, a pronounced overlap between normal eyes and ocular hypertensive eyes.

Keywords: neuroretinal rim width ratios; glaucoma; ocular hypertension     

Tono-Pen determination of intraocular pressure in patients with band keratopathy or glued cornea

AIMS—To evaluate the intraocular pressure (IOP) measurements in patients with band keratopathy or glued corneas obtained from affected and non-affected areas.
METHODS—15 patients with band keratopathy or glued corneas were prospectively recruited. When both eyes were affected, only the right eye was analysed. Tono-Pen readings of IOP were obtained sequentially from the affected and non-affected corneal surface. Additionally, Goldmann applanation tonometry was attempted.
RESULTS—Determination of IOP with the Tono-Pen was possible in all cases, while Goldmann tonometry was not performed in three patients because of severe corneal irregularities. The average of the Tono-Pen readings obtained from the affected cornea (34.8 (SD 14.0) mm Hg) was consistently and significantly higher (p<0.001) than mean IOP obtained by the Tono-Pen from the non-affected area (14.8 (4.3) mm Hg). The average of Goldmann tonometry readings (14.4 (6.1) mm Hg) did not differ significantly from the Tono-Pen values obtained from the non-affected corneal area (p=0.47) but was significantly lower than the Tono-Pen measurements obtained from the affected area (p<0.001)
CONCLUSION—In patients with band keratopathy or glued corneas determination of IOP by Tono-Pen tonometry varies from affected to non-affected area. The Tono-Pen overestimates the level of IOP when it is applied to areas with band keratopathy or with glue.

Keywords: intraocular pressure; applanation tonometry; Tono-Pen; keratopathy     

Visual outcome after paediatric cataract surgery: is age a major factor?

AIMS—To determine functional results after unilateral and bilateral cataract surgery in children with different aphakic optical correction.
METHODS—In this retrospective study, we evaluated visual acuity and binocular vision in 107 children who underwent cataract surgery during the 10 year period from 1985 to 1995. Aphakia was corrected by an intracapsular intraocular lens (IOL), spectacles or contact lenses.
RESULTS—Mean visual acuity was >20/40 (<0.3 log MAR) with normal binocular vision in 58 children over 7 months of age operated on for bilateral cataracts. Pseudophakic eyes regained visual acuity >20/63 (<0.5 log MAR) more often (90%) than aphakic eyes (46%) (p<0.001). Binocular vision was also achieved more often after IOL implantation (p<0.001). Visual outcome of early bilateral cataracts was less satisfactory in children with abnormal foveolar function. For 49 children who had surgery for unilateral cataracts, prognosis was poor when surgery was performed before the age of 7 months. For cataract surgery in older children (7 months) mean visual acuities were better with IOL implantation (p<0.05).
CONCLUSION—Cataract surgery with unilateral and bilateral IOL implantation can provide a beneficial effect on final visual outcome in children who are operated on before abnormal foveolar function develops.

Keywords: binocular vision; intraocular lens; paediatric cataract; visual outcome     

Nd:YAG laser iridotomy in pigment dispersion syndrome: an ultrasound biomicroscopic study

AIMS—Ultrasound biomicroscopy was used to study the shape of the iris and the iridolenticular contact in pigment dispersion syndrome (PDS) eyes, to compare them with matched normal eyes, and to assess the morphological effects of laser iridotomy in PDS eyes.
METHODS—50 eyes of 50 patients suffering from PDS (group 1), and 15 normal eyes of 15 subjects matched for age and refraction (group 2), were studied by ultrasound biomicroscopy (UBM, Humphrey-Zeiss). Nd:YAG laser iridotomy was proposed to the 30 PDS patients with concave iris and 18 underwent the treatment.
RESULTS—The iris was concave in 27 eyes in group 1, and three more eyes showed a concave iris during accommodation. Among normals, iris concavity was present in two eyes. The height of the iris convexity was −0.15 (0.24) mm (range −0.65 to +0.21), in the eyes of group 1, whereas it was +0.07 (0.10) mm (range −0.21 to +0.16) in group 2 (p<0.0012). Group 1 had greater iridolenticular contact than group 2: 1.55 (0.78) mm (range 0.30-2.88) and 1.07 (0.61) (range 0.30-2.50; p=0.0304). After laser iridotomy, only one eye still had a concave iris. Pre- and post-treatment deflections were −0.35 (0.18) mm (range −0.61 to -0.05) and +0.01 (0.06) mm (range −0.12 to +0.17), respectively (p<0.0001). Pre- and post-treatment iridolenticular contact was 2.10 (0.65) mm (range 0.70-2.88) and 0.93 (0.38) mm (range 0.4-1.75), respectively (p<0.0001). After laser iridotomy, the treated irises were flatter than normal (p=0.0207), whereas the iridolenticular contact was not significantly different.
CONCLUSIONS—Laser iridotomy can restore a normal iris shape and iridolenticular contact in eyes suffering from PDS.

Keywords: glaucoma; pigment dispersion syndrome; laser iridotomy; ultrasound biomicroscopy     

Echographic measurements of the retrobulbar optic nerve in normal and glaucomatous eyes

AIM—A study was designed to investigate whether measurements of the optic nerve diameter (OND) and cross sectional area (ONCSA), as measured by B-scan ultrasonography, are altered in glaucoma. The reproducibility and test-retest variability of echographic estimates of retrobulbar optic nerve dimensions was also tested.
METHODS—One eye of 49 glaucoma patients and 90 control subjects underwent five repeated echographic measurements of the maximal interpial diameter and cross sectional area of the orbital optic nerve on two separate occasions. All measurements were taken by one experienced ultrasonographer.
RESULTS—Mean optic nerve diameter (SD) for the control group was 2.86 (0.46) mm, and was independent of height (multiple regression analysis: p = 0.21), axial length (p = 0.74), spherical equivalent (p = 0.97), sex (ANOVA: p=0.36), or race (p=0.14), but was inversely related to age (p = 0.01). Reproducibility of OND readings in control subjects was 0.149 mm (coefficient of repeatability). Test-retest variability of interpial diameter was −0.02 (0.29) mm. Mean interpial diameter of the optic nerve was significantly smaller among glaucomatous eyes (2.58 (0.501) mm) than controls (Mann-Whitney U test: p < 0.0001). Glaucomatous optic nerves also had a significantly smaller cross sectional area (6.68 (2.58) mm²) than those of healthy volunteers (8.25 (1.67) mm²) (p = 0.004).
CONCLUSION—Echographic measurements of the orbital optic nerve are highly reproducible and not subject to clinically meaningful test-retest variability. Optic nerve interpial diameter and cross sectional area are reduced in glaucomatous eyes, reflecting nerve fibre loss. This technique may be useful in distinguishing between normal and glaucomatous eyes where optic disc morphometry is inconclusive or impossible as a result of opaque media.

Keywords: glaucoma; optic nerve; ultrasound     

Oxygen free radical damage in the cornea after excimer laser therapy

AIMS/BACKGROUND—To evaluate the extent of oxygen radical damage in the cornea after excimer laser ablation.
METHODS—The 193 nm argon fluoride excimer laser was programmed for an average fluence of 150 mJ/cm², with a firing rate of 5 Hz and an ablation zone diameter of 6 mm. Phototherapeutic keratectomy was performed to remove 30 µm of epithelium and 50 µm of stroma from the corneas of New Zealand white rabbits. Oxidative tissue damage after laser was determined by measuring oxidised lipids (conjugated dienes and ketodienes) in corneal lipid extracts, and by fast blue B staining to localise the lipid peroxide in the tissue.
RESULTS—Conjugated diene levels were 3.73 (SD 0.56) nmol per hemicornea in ablated corneas and 1.99 (0.33) nmol per hemicornea in normal corneas (p = 0.0044). Ketodiene levels were 2.72 (0.38) nmol per hemicornea in treated corneas and 0.91 (0.12) nmol per hemicornea in normal corneas (p < 0.001). Fast blue B staining disclosed that the tissue damage occurred primarily on the surface of the ablated cornea.
CONCLUSION—The presence of lipid peroxidation in the superficial corneal stroma in excimer laser treated corneas was demonstrated. This lipid peroxidation could be from oxygen free radicals generated by the infiltrating polymorphonuclear cells at the site of tissue damage.