Azithromycin for ocular toxoplasmosis

AIMS—To investigate the efficacy of azithromycin in patients with ocular toxoplasmosis.
METHODS—11 immunocompetent patients with ocular toxoplasmosis were treated with azithromycin (500 mg the first day, followed by 250 mg/day for 5 weeks). Ocular and systemic examinations were performed during active retinitis episodes and all patients were followed for at least 1 year.
RESULTS—The intraocular inflammation disappeared within 4 weeks in seven patients, including two cases with progressive retinitis despite previous treatment with pyrimethamine, sulphadiazine, and folinic acid. Recurrence of retinitis occurred in three patients (27%) within the first year of follow up. No systemic side effects of azithromycin were encountered.
CONCLUSION—These results indicate that although azithromycin cannot prevent recurrent disease it may be an effective alternative for patients with ocular toxoplasmosis who cannot tolerate standard therapies.

Keywords: azithromycin; ocular toxoplasmosis     

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.

     

Possible role for nitric oxide releasing nerves in the regulation of ocular blood flow in the rat

AIM—To investigate the role of nitrergic nerves in the regulation of ocular blood flow.
METHODS—Conscious, lightly restrained rats were treated with either the neuronal nitric oxide synthase inhibitor 7-nitroindazole (7-NI), or the non-selective inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), and ocular blood flow was measured ex vivo from tissue samples, using the fully quantitative [14C]-iodoantipyrine technique.
RESULTS—In the peripheral circulation, L-NAME produced an increase in arterial blood pressure (+22%) while 7-NI had no effect. In contrast, both 7-NI and L-NAME produced significant decreases in ocular blood flow (−31% and −59% respectively). The ocular vascular resistance calculated from ocular blood flow and mean arterial blood pressure increased by 29% following 7-NI, but by 130% following L-NAME.
CONCLUSIONS—Nitric oxide releasing neurons may play an important contributory role in regulating ocular blood flow.

Keywords: nitric oxide; neuronal nitric oxide synthase; 7-nitroindazole; NG-nitro-L-arginine methyl ester; ocular blood flow     

Ocular manifestations of familial amyloidotic polyneuropathy type I: long term follow up

AIMS—To obtain precise information on ocular manifestations of familial amyloidotic polyneuropathy (FAP) type I, the incidence of five main ocular manifestations—abnormal conjunctival vessels (ACV), keratoconjunctivitis sicca (KCS), pupillary abnormality, vitreous opacity, and glaucoma, were compared through long term follow up.
METHODS—Ocular examinations were performed in 37 FAP type I patients (Met30) from once to 12 times over a period of 1 to 12 years and 7 months.
RESULTS—The following incidences were observed on initial examination of each patient with FAP: ACV in 75.5%, pupillary abnormalities in 43.2%, KCS in 40.5%, glaucoma in 5.4%, and vitreous opacity in 5.4%. All ocular manifestations increased with the progression of FAP, and the incidence of ACV reached 100% during follow up: this may be helpful in the diagnosis of FAP.
CONCLUSION—Since no precise statistical ocular study on FAP with long term follow up has been performed, this report may provide important information to help elucidate the mechanism of the amyloid distributing process in the amyloid targeted organs of FAP and to provide the natural course of ocular manifestations of FAP.

     

Ocular complications of heart, lung, and liver transplantation

AIM—To document the nature and frequency of ocular complications in a large group of patients who underwent heart, lung, or liver transplantation.
METHODS—A retrospective audit of the medical records of all patients undergoing heart, lung, or combined heart-lung transplantation at St Vincent's Hospital, Sydney, or liver transplantation at Royal Prince Alfred Hospital Sydney, was performed to detect patients with symptomatic ocular complications following transplantation. 19 of 860 patients were identified as having ocular complications.
RESULTS—Ocular complications occurred in 2% of patients with 65% of these being opportunistic infections. Herpes group viral retinitis (77%) and fungal chorioretinitis (22%) were seen. Other complications included choroidal pseudolymphoma, central retinal vein occlusion, herpes zoster ophthalmicus, herpetic keratitis, dacryocystitis, cyclosporin retinopathy, and rifabutin associated uveitis.
CONCLUSION—Herpes group viral retinitis was the most common ocular opportunistic infection and occurred most frequently during the second year after transplantation. Delayed diagnosis was associated with poor visual outcome.

Keywords: ocular complications; heart transplantation; lung transplantation; liver transplantation; herpetic ocular infections     

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     

Long term course of tear gland function in patients with keratoconjunctivitis sicca and Sjögren's syndrome

AIMS—To assess the course of tear gland function of patients with keratoconjunctivitis sicca (KCS) associated with primary (KCS-PSS) or secondary Sjögren's syndrome (KCS-SSS), and of patients with KCS not related to Sjögren's syndrome (KCS-NS).
METHODS—In 106 patients with dry eye an ophthalmic diagnosis of KCS was made. Subsequent evaluations revealed a diagnosis of KCS-PSS in 31, KCS-SSS in 19, and KCS-NS in 56 patients. Follow up assessments have been performed 10-12 years after initial diagnosis.
RESULTS—At baseline and at follow up tear gland function tests were worse in patients with KCS-PSS compared with the other forms of KCS. At follow up in the KCS-SSS patient group the tear gland function variables returned to marginal normal limits. In contrast with expectation, a marked improvement of the tear gland function variables in the KCS-NS patient group was noted.
CONCLUSIONS—In KCS-PSS patients tear gland function is characterised by a steady state situation. In KCS-SSS patients the normalisation of tear gland function variables most probably reflects a remission of the underlying disease. In view of the overall improvement in KCS-NS patients the term age related KCS should be avoided.

     

Bilateral, anterior stromal ring opacity of the cornea

AIMS/BACKGROUND—To describe a bilateral, mid peripheral, ring-shaped corneal opacity, not resembling any known corneal degeneration, dystrophy, or other disorder, and occurring without ocular or systemic disease.
METHODS—Ophthalmic examination, haematological screening, and ultrasound biomicroscopy.
RESULTS—A 25 year old man showed grey-white, granular opacities in both corneas, with an 8 mm diameter ring configuration, and a V-shaped distribution in the anterior stroma. The surrounding corneal stroma was clear, and the tear film, the epithelium and its basement membrane, Descemet's membrane, and the endothelium were normal. Evidence of systemic disease was not found. Family members did not show corneal abnormalities.
CONCLUSION—A bilateral corneal ring opacity may occur in healthy, asymptomatic, young people. These corneal rings may result from depositions of unknown origin, or possibly a rare corneal dystrophy.

Keywords: cornea; corneal opacity; corneal rings     

Systemic and local immunological features of atopic dermatitis patients with ocular complications

AIMS—Clinical factors and data from recent cases of atopic dermatitis (AD) (with or without ocular complications) and non-AD cases were examined to evaluate the mechanism of atopic ocular complications.
METHODS—IgE-RAST for eight allergens including rice, egg, and mite and serum total IgE were measured in 216 patients with AD (70 ocular type, 146 non-ocular type) and 69 non-AD individuals. Tear histamine and leukotriene B₄ (LTB₄) levels were also measured.
RESULTS—The serum levels of IgE were significantly increased in AD patients with ocular complications compared with those without ocular complications. The positive rates of IgE-RAST for rice and wheat were significantly higher in ocular type AD than in non-ocular type AD. In ocular type AD, serum IgE was significantly increased in patients with cataract compared with that in those without cataract. Tear histamine and LTB₄ levels in AD patients with ocular complications showed significant elevations compared with those in patients with pure AD and controls.
CONCLUSIONS—These results suggest that ocular type AD belongs to the most severe end of the spectrum of AD, and that some food antigens may contribute to the pathogenesis of severe AD resulting in ocular complications.

Keywords: atopic dermatitis; IgE-RAST; histamine; leukotriene B₄     

Eosinophil granule proteins expressed in ocular cicatricial pemphigoid

BACKGROUND—Blister formation and tissue damage in bullous pemphigoid have been attributed to the release of eosinophil granule proteins—namely, to eosinophil derived cationic protein (ECP) and major basic protein (MBP). In the present investigation these eosinophil granule proteins were studied in the conjunctiva of patients with ocular cicatricial pemphigoid (OCP).
METHODS—Conjunctival biopsy specimens obtained from patients with subacute (n=8) or chronic conjunctival disease (n=13) were analysed histologically and immunohistochemically using antibodies directed against EG1 (stored and secreted ECP), EG2 (secreted ECP), MBP, CD45 (common leucocyte antigen), CD3 (pan T cell marker), and HLA-DR (class II antigen).
RESULTS—Subepithelial mononuclear cells, mast cells, and neutrophils were detected in all specimens. The number of mononuclear cells, neutrophils, CD45+ cells, CD3+ cells, and the HLA-DR expression were significantly higher in the subacute than in the chronic disease group. Some eosinophils were found in specimens from five of eight patients with subacute OCP, but in none of the patients with chronic disease. The eosinophil granule proteins (ECP and MBP) were found in the epithelium and substantia propria in patients with subacute conjunctivitis.
CONCLUSIONS—Subepithelial cell infiltration in the conjunctiva greatly differs between subacute and chronic ocular cicatricial pemphigoid specimens. The findings suggest that eosinophil granule proteins may participate in tissue damage in acute phase of inflammation in OCP.

     

Effect of chronic inhibition of nitric oxide synthase on ocular blood flow and glucose metabolism in the rat

AIMS—To investigate the effects of chronic administration of nitric oxide synthase inhibition on ocular blood flow and metabolic demand in the rat and to compare these effects with changes in the cerebral and peripheral circulation.
METHODS—Male Sprague-Dawley rats were injected with the nitric oxide synthase inhibitor L-NAME (75 mg/kg ip), either on a single occasion only or once daily for 10 consecutive days. Controls were injected with saline. Regional blood flow and glucose metabolism were measured from tissue samples, using [¹⁴C]-iodoantipyrine and [¹⁴C]-2-deoxyglucose respectively, 1 hour after either acute L-NAME injection or 1 hour after the last injection of the chronic treatment protocol.
RESULTS—Mean arterial pressure was significantly increased (+31%) following the acute injection (indicating peripheral vasoconstriction) and this effect was enhanced (+50%) following chronic treatment. In both the ocular and cerebral circulation, blood flow was decreased following acute treatment (−48% and −43% respectively). However, while this response was totally attenuated in the cerebral circulation following chronic L-NAME treatment (−4%), the ocular circulation remained responsive (−57%). Metabolic demand in brain and eye tissue, as reflected in the accumulation of 2-deoxyglucose, was unaffected by either acute or chronic treatment with L-NAME.
CONCLUSION—Homeostatic mechanisms appear to be activated in the cerebral circulation which re-establish flow metabolism homeostasis, and the effect of L-NAME on cerebral blood flow is attenuated following repeated exposure. This process does not seem to happen in the ocular circulation and, thus, the ocular vasculature appears to behave more like those blood vessels which determine total peripheral resistance than the cerebral circulation. It remains to be seen whether the sustained decrease in blood flow in the eye is sufficient to compromise ocular function and render the eye susceptible to damage from chronic L-NAME induced oligaemia.

     

Increased presence of Epstein-Barr virus DNA in ocular fluid samples from HIV negative immunocompromised patients with uveitis

AIMS—To investigate whether routine testing for Epstein-Barr virus (EBV) is necessary in the examination of a patient with uveitis.
METHODS—Intraocular EBV DNA was determined in 183 ocular fluid samples taken from patients with AIDS and uveitis, HIV negative immunocompromised uveitis, acute retinal necrosis, toxoplasma chorioretinitis, intraocular lymphoma, anterior uveitis, and miscellaneous uveitis of unknown cause. In 82 samples from this group of patients paired serum/ocular fluid analysis was performed to detect local antibody production against EBV. Controls (n=46) included ocular fluid samples taken during surgery for diabetic retinopathy, macular pucker, or cataract.
RESULTS—Serum antibody titres to EBV capsid antigen proved to be significantly increased in HIV negative immunocompromised patients with uveitis (p<0.01) compared with controls. Local antibody production revealed only three positive cases out of 82 patients tested, two results were borderline positive and one patient had uveitis caused by VZV. EBV DNA was detected in three out of 46 control ocular fluid samples. In the different uveitis groups EBV DNA was noted, but was not significantly higher than in the controls, except in six out of 11 HIV negative immunocompromised patients (p=0.0008). In four out of these six cases another infectious agent (VZV, HSV, CMV, or Toxoplasma gondii) had previously been identified as the cause of the uveitis.
CONCLUSIONS—When comparing various groups of uveitis patients, EBV DNA was found more often in HIV negative immunocompromised patients with uveitis. Testing for EBV does not have to be included in the routine management of patients with uveitis, since indications for an important role of this virus were not found in the pathogenesis of intraocular inflammation.

Keywords: Epstein-Barr virus; intraocular fluid; polymerase chain reaction; uveitis     

Effectiveness of hyaluronan on corneal epithelial barrier function in dry eye

AIMS/BACKGROUND—The aim of this study was to assess quantitatively the effectiveness of hyaluronan on corneal disruption in patients with dry eye. Corneal epithelial barrier function was evaluated by measuring fluorescein permeability using a slit-lamp fluorophotometer.
METHODS—11 patients with dry eye were assigned to this study. Hyaluronan ophthalmic solution (0.1% hyaluronic acid) was instilled five times a day to the right eye, in addition to the usual artificial tear solutions. The left eye received only the artificial tear solutions. Corneal barrier function was evaluated on the pretreatment day, and at 2 and 4 weeks after treatment. Fluorophotometry was used to measure fluorescein uptake at the central and lower corneal portions.
RESULTS—Two weeks after treatment, hyaluronan treated right corneas showed significant corneal epithelial barrier improvement in the lower portion, compared with the pretreatment day (p<0.025). Four weeks after treatment, the treated corneas showed significant improvement in the central corneal portion (p<0.025) and improvement in the lower portion, compared with the pretreatment day. The untreated left corneas, on the other hand showed no improvement during the course of the study.
CONCLUSION—This study suggests that hyaluronan is effective in the treatment of corneal epithelial disruption in dry eye.

     

Ocular contact time of a carbomer gel (GelTears) in humans

BACKGROUND/AIMS—Carbomers are widely used in products for the treatment of dry eye; however, the polymer gel thins on addition of probes (for example, fluorescein salt) confounding the comparison of products by objective clinical tests such as spectrophotofluorimetry or scintigraphy. A novel method of radiolabelling carbomer gels, with minimum change to their rheology, has permitted the non-invasive evaluation of precorneal residence of the gel in volunteers using gamma scintigraphy. The technique was used to evaluate the precorneal clearance of the liquid phase and of a suspended particulate in GelTears.
METHODS—Low sodium technetium-99m labelled diethylenetriaminepentacetic acid (^99mTc-DTPA) was used to label carbomer 940 gel, either adsorbed onto sterile charcoal to model an entrapped drug, or added directly to the gel to a final activity of 1 MBq per 25 µl dose. The clearance of the labelled gels was then compared with ^99mTc-DTPA labelled saline in 12 volunteers.
RESULTS—The addition of the low sodium radiopharmaceutical produced insignificant rheological changes in the gel compared with conventional ^99mTc-DTPA labelling. The residence times on the eye of the gel formulations were significantly greater than that of the saline control. At 8 minutes postdosing, the label levels retained (mean (SD)) on the ocular surface were: saline, 7% (7%); ^99mTc-DTPA gel, 42% (27%); and ^99mTc-carbon gel, 42% (20%) of administered dose. There was no difference observed in the precorneal distribution between ^99mTc-DTPA solution and particulate markers.
CONCLUSIONS—These data demonstrate that carbomer based gels significantly extend contact of solutes or suspended solids with the corneal surface. The method of labelling does not significantly change the initial viscosity and is superior to previous methods which have used sodium salts (for example, sodium fluorescein) and therefore underestimate contact time.

Keywords: carbomer gels; viscosity; ocular contact time; dry eye syndrome     

Efficacy of probing as treatment of epiphora in adults with blocked nasolacrimal ducts

AIMS—To determine the efficacy of probing in the initial treatment of epiphora and the symptom free period in adults with blocked nasolacrimal ducts.
METHODS—The results of probing in 85 eyes with epiphora due to nasolacrimal duct obstruction were studied retrospectively after a mean follow up of 7.4 months (SD 11.6) by a questionnaire and interview survey of patients.
RESULTS—35% of the eyes had an outcome of no watering after probing, 17% mild watering, 35% moderate watering, and 11% severe watering. The patients' satisfaction (watering subjectively improved) after undergoing this procedure was 82%, which is higher than previously reported. The mean symptom free period in eyes with no watering was 11.25 months, in eyes with mild watering 8.20 months, in eyes with moderate watering 5.35 months, and in eyes with severe watering 0.95 months. There was a significant difference (p=0.001) in the symptom free period between the no watering and severe watering groups.
CONCLUSIONS—Probing in adults with confirmed nasolacrimal duct obstruction can be recommended as an initial treatment procedure because of its relatively good efficacy and high patient satisfaction without compromising subsequent surgical treatment if unsuccessful.

Keywords: epiphora; nasolacrimal ducts; probing     

Bacterial keratitis in the critically ill

BACKGROUND—In the 4 year period (1988-91) there were nine cases of bacterial keratitis in five critically ill patients on an intensive care unit (`unit A'), all except one due to Pseudomonas aeruginosa. Many of these patients had serious ocular complications requiring surgery and all surviving patients were left with significant visual deficits. One further case of keratitis due to P aeruginosa occurred on unit A in April 1993. The problem of keratitis in ventilated patients is not unique to this unit as a further four cases in three patients from additional units in this area have been treated.
METHODS—Predisposing factors in unit A were established through subsequent investigations. It was found, in particular, that all the ocular infections were preceded by colonisation of the respiratory tract with the pathogenic organism. Recommendations concerning eye care and tracheal suctioning were adopted by unit A in 1991.
RESULTS—In the subsequent 4 years (1991-5), the frequency of isolation of pseudomonas from the respiratory tract per patient treated in unit A remained relatively high at 3.8% (153/4032). However, the conjunctival pseudomonas isolation rate has decreased significantly (p <0.001) from 0.8% (19/2430) to 0.05% (2/4032).
CONCLUSIONS—Ventilated patients may be at risk from inoculation of pathogens into the eyes. The principal risk factor for bacterial keratitis in this series was corneal exposure secondary to conjunctival chemosis or lid damage. The adoption of simple preventative measures on unit A had a significant impact on the incidence of eye infections due to pseudomonas, despite the high proportion of patients whose respiratory tracts were colonised with the same organism. There is a need for additional research into the most effective method of eye care for ventilated patients in order to reduce the frequency of this avoidable condition.

     

Detection of human papillomavirus infection in squamous tumours of the conjunctiva and lacrimal sac by immunohistochemistry, in situ hybridisation, and polymerase chain reaction

BACKGROUND—Squamous tumours of the ocular surface, including the lacrimal pathway, range from benign lesions to invasive carcinomas. Some of these tumours are associated with human papillomavirus (HPV) infection, with the types of HPV differing among papillomas and dysplastic or malignant lesions.
METHODS—The relation between squamous tumours of the conjunctiva and lacrimal sac and HPV infection was investigated in 17 individuals with such tumours. Nine of the 17 tumours were benign, four were dysplastic lesions, and four were carcinomas.
RESULTS—Eight specimens showed positive immunohistochemical staining with antibodies to HPV; four of these eight were papillomas, three were dysplastic lesions, and one was a carcinoma. Koilocytosis was detected in seven of these eight tumours. Five of the eight specimens positive for immunohistochemical staining were also positive for HPV DNA by in situ hybridisation, and all eight were positive for HPV DNA by the polymerase chain reaction (PCR) method.
CONCLUSION—Approximately 50% of squamous tumours of the ocular surface and lacrimal sac were associated with HPV infection. This is the first report, to our knowledge, of the detection of HPV in the field of ophthalmology by a combination of immunohistochemistry, in situ hybridisation, and PCR.

     

Coronal approach for rehabilitative orbital decompression in Graves' ophthalmopathy

AIMS—To determine the effectiveness and safety of three wall orbital decompression by the coronal approach in Graves' ophthalmopathy.
METHODS—The records of 125 patients with Graves' ophthalmopathy, who had undergone three wall orbital decompression by coronal approach between April 1984 and October 1993, were studied retrospectively. Special attention was paid to proptosis reduction, changes in ocular motility, and complications.
RESULTS—The preoperative Hertel values ranged from 15 to 30 mm (mean 22.43 mm). The mean proptosis reduction was 4.34 mm (range 0-10 mm). Proptosis reduction in patients with preoperative Hertel values higher than 27 mm was significantly more than in patients with preoperative values between 25 and 27 mm (p < 0.05). This last group showed significantly more proptosis reduction than patients with preoperative Hertel values of 23 and 24 mm (p < 0.01). Postoperatively, 3.2% of the patients showed new diplopia in primary and/or reading position. In 4% of the patients with normal ocular motility preoperatively, diplopia in the extreme directions of gaze developed. In 4% of the patients, preoperative motility disturbances decreased or disappeared postoperatively.
CONCLUSION—Three wall orbital decompression by coronal approach is a safe and effective technique, to achieve proptosis reduction in patients with Graves' ophthalmopathy, with fewer complications than other techniques thus far described.

     

"Johnny Poppers": a cause of serious ocular injury

AIMS/BACKGROUND—The causes of blunt ocular trauma are many and diverse. We present two cases of ocular injury caused by an unusual form of weapon called a "Johnny Popper". There follows a theoretical and experimental evaluation of the velocity of the projectiles fired by this device.
METHODS—A Johnny Popper was constructed under expert guidance. The elastic properties of the device were measured and this allowed calculation of a theoretical exit velocity of the projectiles fired. The weapon was subsequently fired under test conditions which permitted the exit velocity of the projectiles fired to be measured directly.
RESULTS—The theoretical velocity of the projectiles was calculated as 80 ms^-1 and the experimentally measured velocity was 57 ms^-1.
CONCLUSIONS—Johnny Poppers are a previously undescribed and unique form of home made weapon. They are intended for playful mischief, but have the potential to cause serious ocular trauma.

     

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