Evaluation of Hemifield Sector Analysis Protocol in Multifocal Visual Evoked Potential Objective Perimetry for the Diagnosis and Early Detection of Glaucomatous Field Defects

PURPOSE: Multifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. METHODS: Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system. RESULTS: Analysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively. CONCLUSIONS: The new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

Evaluation of Hemifield Sector Analysis Protocol in Multifocal Visual Evoked Potential Objective Perimetry for the Diagnosis and Early Detection of Glaucomatous Field Defects

PURPOSE: Multifocal visual evoked potential (mfVEP) is a newly introduced method used for objective visual field assessment. Several analysis protocols have been tested to identify early visual field losses in glaucoma patients using the mfVEP technique, some were successful in detection of field defects, which were comparable to the standard automated perimetry (SAP) visual field assessment, and others were not very informative and needed more adjustment and research work. In this study we implemented a novel analysis approach and evaluated its validity and whether it could be used effectively for early detection of visual field defects in glaucoma. METHODS: Three groups were tested in this study; normal controls (38 eyes), glaucoma patients (36 eyes) and glaucoma suspect patients (38 eyes). All subjects had a two standard Humphrey field analyzer (HFA) test 24-2 and a single mfVEP test undertaken in one session. Analysis of the mfVEP results was done using the new analysis protocol; the hemifield sector analysis (HSA) protocol. Analysis of the HFA was done using the standard grading system. RESULTS: Analysis of mfVEP results showed that there was a statistically significant difference between the three groups in the mean signal to noise ratio (ANOVA test, p < 0.001 with a 95% confidence interval). The difference between superior and inferior hemispheres in all subjects were statistically significant in the glaucoma patient group in all 11 sectors (t-test, p < 0.001), partially significant in 5 / 11 (t-test, p < 0.01), and no statistical difference in most sectors of the normal group (1 / 11 sectors was significant, t-test, p < 0.9). Sensitivity and specificity of the HSA protocol in detecting glaucoma was 97% and 86%, respectively, and for glaucoma suspect patients the values were 89% and 79%, respectively. CONCLUSIONS: The new HSA protocol used in the mfVEP testing can be applied to detect glaucomatous visual field defects in both glaucoma and glaucoma suspect patients. Using this protocol can provide information about focal visual field differences across the horizontal midline, which can be utilized to differentiate between glaucoma and normal subjects. Sensitivity and specificity of the mfVEP test showed very promising results and correlated with other anatomical changes in glaucoma field loss.

Management of non-penetrating traumatic hyphema in ophthalmology department of HMC. Review of 83 cases

To review the management strategy of non-penetrating traumatic hyphema in ophthalmology department of HMC [Hamad Medical Corporation] and compare it with other international approaches. This is a retrospective study for evaluating the management of non-penetrating traumatic hyphema in the Ophthalmology Department of Hamad Medical Corporation. Records of 83 patients over the period between January 1999 and May 2003 were studied for various criteria including: demographic factors; causes; severity and type of hyphema; visual and intraocular pressure outcome; and application and outcome of medical and surgical treatment. Patients' criteria and treatment policy was compared with other studies.Visual acuity as defined according to the WHO system. Total of 83 patients; 76% males and 24% females, their average age was 24.4 years. The majority had hyphema due to work trauma 45.8%, 76% recovered 6/12 or better vision within one month, 14% developed glaucoma, 2.4% complicated by corneal blood staining. Mydriatics were used in 65%, 5% had rebleeding. All the patients were treated as inpatients, only one case required surgical intervention for uncontrolled IOP and early corneal staining. Dependent on the findings of our study and other studies, we rationalized alterations to be concerned according to Qatar locality, however, the general outcome of traumatic hyphema in our department was not bad

Keratoplasty in Qatar

To evaluate the indications and outcome of keratoplasty in Qatar, and to outline the main difficulties associated with keratoplasty in Qatar. A retrospective review of all keratoplasties performed at the Hamad Medical Corporation in the last 7 years regarding indications, procedures and outcome was carried out. Seventy-nine keratoplasties in 72 patients were evaluated. The mean age and was 50 years [SD+19.3]. The leading indications in order of frequency were keratoconus [30.4%], bullous karatopathy [24.1%], corneal opacities [21.5%], re-grafting [15.2%], corneal dystrophy [5.1%] and traumatic corneal scarring. Regarding outcome, clear graft was achieved in 57 eyes. The main causes for a poor outcome were glaucoma and graft rejection. The encouraging outcome of keratoplasties in Qatar has inspired us to launch a campaign for corneal donation to meet the increasing demand for graft materials and to propose the establishment of a national eye bank