Optic disc duplication or coloboma?

AIM: To describe lesions resembling optic disc duplication and highlight their unusual visual fields. The authors also report the first case of pseudo-duplication of the optic disc with overlying retinal nerve fibre layer. METHODS: Retrospective, non-comparative review of case notes. Humphrey visual fields and OCT-3 imaging were performed. RESULTS: All 11 cases represented peripapillary chorioretinal coloboma, some of which lie superior to the optic disc. A double blind spot or superior hemifield defects can be demonstrated by automated visual field testing. CONCLUSION: Clinical examination and identification of bridging retinal vessels from the true optic disc to the second pseudo disc can usually avoid unnecessary invasive and non-invasive investigations.     

Are optic disc drusen inherited?

OBJECTIVE: To conduct family studies of the incidence of optic disc drusen and related optic disc anomalies among relatives of those affected. DESIGN: Retrospective case series with prospective examination of patients and their relatives using B-scan ultrasonography and color photography. PARTICIPANTS: A total of 27 relatives of 7 probands with bilateral optic disc drusen were examined. MAIN OUTCOME MEASURES: Presence of optic disc drusen on clinical examination or B-scan ultrasonography and presence of related anomalies, including absence of optic disc cup and presence of anomalous vasculature. RESULTS: Only 1 of 27 relatives had optic disc drusen (3.7%). Thirty of 53 eyes had anomalous vessels (57%), and 26 eyes had no optic cup (49%). CONCLUSION: The primary pathology of optic disc drusen is likely to be an inherited dysplasia of the optic disc and its blood supply, which predisposes to the formation of optic disc drusen.     

Optic disc morphology in “age-related atrophic glaucoma”

Background: This study was performed in order to evaluate whether, in primary open-angle glaucoma (POAG), patients with a different degree of fundus tessellation vary in optic disc morphology and level of intraocular pressure Methods: Color stereo optic disc photographs of 562 patients with POAG and a myopic refractive error of less than –8 diopters were morphometrically examined. According to the degree of fundus tessellation, the total group was divided into a tessellated subgroup (n = 256) and a nontessellated subgroup (n = 306,) both matched for neuroretinal rim area and refractive error Results: In the tessellated subgroup, as compared to the nontessellated subgroup, the mean maximal intraocular pressure values were significantly lower, the parapapillary atrophy was significantly larger, the optic cup was significantly more shallow, frequency of disc hemorrhages was lower, the mean visual field defect was significantly more marked, and patient age was significantly higher. Within the whole study group, the degree of fundus tessellation increased significantly (P<0.005) with decreasing mean maximal intraocular pressure, decreasing optic cup depth, and increasing degree of parapapillary atrophy. In the subgroups with the highest degree of fundus tessellation, parapapillary atrophy was the greatest and the mean maximal intraocular pressure was the lowest compared to other subgroups Conclusion: At the low-pressure end of POAG, marked fundus tessellation is associated with large parapapillary atrophy, shallow disc cupping, mostly concentric emaciation of the neuroretinal rim, and high patient age. The results suggest a distinct subtype of POAG in older patients with relatively low intraocular pressure leading to a mainly diffuse atrophy of the optic nerve.     

Unilateral disc edema as the first presentation of chronic myeloid leukemia

Dear Editor,We report the first case of unilateral optic disc edema as the first presentation of chronic myeloid leukemia(CML)approximately one year prior to substantial elevation in white blood cell(WBC)count and subsequent diagnosis of CML.Ocular manifestations of leukemia are well recognized。     

Is the nasal optic disc sector important for morphometric glaucoma diagnosis?

BACKGROUND/AIM: Since the central retinal vessel trunk usually located in the nasal optic disc sector can render difficult the delineation of the neuroretinal rim and optic disc, the aim of this study was to evaluate whether the nasal region of the optic nerve head is important, or can be left out, for the morphometric glaucoma diagnosis. METHODS: The clinical observational study included 1337 patients with primary or secondary open angle glaucoma and 649 normal subjects. The glaucoma group was divided into 1187 patients with glaucomatous visual field defects ("perimetric glaucoma"), and into 150 patients with optic nerve head changes and normal visual fields ("preperimetric glaucoma"). Colour stereo optic disc photographs were morphometrically evaluated. RESULTS: Highest diagnostic power for the separation between the normal group and the perimetric glaucoma group, and for the differentiation between the normal group and the preperimetric glaucoma group, had the sum of inferotemporal rim area plus superotemporal rim area, the sum of inferotemporal rim area plus superotemporal rim area plus temporal rim area, and the inferotemporal rim area as single parameter. The lowest diagnostic precision had the nasal rim area as single parameter or in combination with rim measurements in other disc sectors. CONCLUSION: Excluding the nasal optic disc sector does not markedly decrease the diagnostic power of morphometric optic disc analysis in glaucoma diagnosis. It may have importance for an automated computerised morphometric detection of glaucomatous optic nerve damage.     

Optic disc pit combining with an optic nerve cyst — A case report

Herein, we report a case presenting with the optic disc pit and optic nerve cyst coexistence. A 54-year-old female presented to our office with progressive blurred vision for up to 3 months in her left eye. Upon examination, the best corrected visual acuity in the right eye was 20/20 and in the left eye was 20/100. Fundoscopic examination revealed a black pit at the temporal margin of left optic disc without obvious macular edema. Findings were confirmed later with optical coherence tomography (OCT) examination. Further magnetic resonance imaging (MRI) disclosed a well defined 6 mm x 6mm cystic lesion located at temporal aspect of left retro-bulbar optic nerve within the optic nerve sheath. Compression of left optic nerve was prominent. Visual evoked potential (VEP) test verified dysfunction of left optic nerve. She kept following up for 6 months. Neither maculopathy nor retinal edema occurred during this period. The visual acuity maintained 20/100 in her left eye. The size and location of optic disc pit remained as well. To sum up, in a patient with visual impairment combing with optic disc pit, further imaging surveys should be considered to exclude the possible coexistence of other optic nerve abnormalities.     

Can an inexperienced observer accurately plot disc contours using Heidelberg retinal Tomograph?

Objective

To examine the reliability of inexperienced observers in plotting optic disc contours on Heidelberg retinal tomography images before and after training.

Design

Observational study.

Participants

One hundred eyes that were randomly selected from the Singapore Indian Eye Study.

Methods

Both eyes of subjects were imaged with Heidelberg Retina Tomograph 3 (HRT-3; Heidelberg Engineering, Heidelberg, Germany). Optic disc contours were plotted on the same images by 2 new observers on 2 separate occasions, before and after 2-hour standardized training on the skills and tools available to accurately identify and delineate optic disc contours. These plottings were compared with an experienced, trained glaucoma expert (gold standard). Agreement and variability were analyzed by interclass correlation tests and Bland–Altman plots.

Results

A total of 182 images (18 excluded because of poor quality) from 89 Indian subjects were included. The mean age was 53.27 ± 7.25 years and 54.8% were male. There was moderate-to-high agreement between pretraining (both new observers) and experienced observer’s results (interclass correlation values range, 0.76–0.99). The interclass correlation improved for all the HRT-3 parameters after the 2 new observers were adequately trained. Comparing the interclass correlation values before and after training, the differences for mean retinal nerve fibre layer thickness for Observer 1 and all the HRT-3 parameters for Observer 2 were statistically significant.

Conclusions

This study shows that it is easy to train a new inexperienced observer to plot optic disc contours on HRT images, which translates into improved and acceptable interobserver variability and agreement.     

Imaging of the optic disc in glaucoma: which way to go?

Less than 10 years ago, fundus photography was believed to be the only method to document optic disc changes in glaucoma. Since then, many sophisticated electronic devices have been developed to supersede conventional photography. At the moment, confocal laser scanning tomography, nerve fiber layer polarimetry, and optical coherence tomography are the most popular techniques. The current status of optic disc imaging in glaucoma can (in our very subjective opinion) be summarized as follows. Confocal laser scanning tomography is the most comprehensively tested electronic modality. It is perhaps the method of choice in major glaucoma centers. Nerve fiber layer polarimetry has forged ahead during the past 2 years and may become an alternative to confocal laser scanning tomography in the future. Optical coherence tomography is a fascinating technique, which may also become important in the future. Right now, however, it is still in the experimental stage. Conventional disc photography--despite all those new techniques--still has its place. Perhaps it is the method of choice in routine glaucoma practice, except those clinics that can afford one of the "high tech" machines.     

Morphological changes in the optic disc after vitrectomy and fluid–air exchange

Background Although many investigators have previously reported various ocular complications induced by vitrectomy, little is known about post-operative morphological changes in the optic disc. The purpose of this study is to evaluate the effect of vitrectomy and fluid–air (F-A) exchange on the post-operative morphology of the optic disc.Methods We examined 31 eyes that had undergone vitrectomy for macular holes (22 eyes) or epiretinal membranes (9 eyes). Only the patients with macular holes were treated by fluid–air exchange. Morphological changes in the optic disc were evaluated using the Heidelberg Retina Tomograph.Results C/D area ratios significantly decreased for 6 months post-operatively. The rim volumes significantly increased for 1 month following surgery. Cup volumes significantly decreased at 3 months after surgery. No significant change of mean cup depth was observed post-operatively. The eyes that had not been subjected to F-A exchange showed no significant morphological change following surgery. In contrast, the eyes that had undergone F-A exchange showed significant decrease in C/D area ratio and cup volume and an increase in rim volume and mean cup depth for considerable periods following surgery. Any of the patients showed no post-operative visual field loss.Conclusion Whereas no visual field loss is observed, vitrectomy with F-A exchange induces morphological changes in the optic disc for significant periods following surgery.     

Retinal and disc neovascularization in Behçet's disease and efficacy of laser photocoagulation

Background: The vasoocclusive episodes resulting from Behçet's disease can cause capillary dropout and vascular remodeling. Retinal and disc neovascularizations, which occur as a result of occlusive vasculitis, can cause recurrent vitreal hemorrhages and neovascular glaucoma leading to severe visual impairment. Methods: 1080 eyes of 540 patients with Behçet's disease were examined between 1973 and 1993. Of the 912 eyes with posterior segment involvement, laser photocoagulation could be performed in 13 of 25 eyes with disc neovascularization (NVD), 12 of 22 eyes with retinal neovascularization (NVE), and 4 of 6 eyes with NVD and NVE. Laser was directed at areas of NVE and retinal capillary nonperfusion. In cases of NVD, panretinal photocoagulation was performed. Results: The rate of regression of NVD was significantly greater in laser-treated eyes than in the untreated group. The results were similar in cases of NVD with NVE. In eyes with NVE which underwent laser photocoagulation, the NVE regressed. None of the treated eyes developed neovascular glaucoma during the follow-up period. Vitreous hemorrhage occurred in two laser-treated eyes. Conclusion: Laser photocoagulation is successful in preventing complications of retinal and disc neovascularizations. Thus, in cases of occlusive vasculitis associated with Behçet's disease, laser photocoagulation should be considered for prevention of complications such as vitreous hemorrhage and neovascular glaucoma.Presented at the meeting of the Club Jules Gonin, Versaille, France, 8-13 September 1994     

How large is the optic disc? Systematic errors in fundus cameras and topographers

PURPOSE: To determine whether or not there are systematic differences in the areas of optic discs as measured by different machines using different measurement algorithms and whether racial or gender differences exist in optic disc area measurements. METHODS: We examined the results of twenty-three published studies on the size of normal optic discs of various patient populations. Studies differed in the type of instrument and method used to measure optic disc area, and the number, age, race and gender of subjects examined. Noticing that different machines exhibited statistically significant systematic differences in optic disc sizes of comparable populations, we computed a "normalization" factor for each machine based on these mean differences. Applying this normalization factor to the results, we then re-examined the differences between racial and gender groups. RESULTS: By comparing the results of mean optic disc areas of different racial groups made with different machines, and normalizing results according to those of the Zeiss fundus camera, we found the normalization factors for the following machines to be, Zeiss fundus camera: 1 (by definition), Rodenstock Optic Disc Analyzer (RODA): 1.51, Topcon fundus camera: 1.04, Heidelberg Retina Tomograph (HRT): 1.15 and TopSS scanning laser ophthalmoscope: 1.29. That is, to bring the results of area measurements made with a RODA machine in line with those made with a Zeiss fundus camera, one should multiply the former by the factor 1.51. Using the normalized results, we confirmed the findings of previous authors that the optic disc areas of black subjects were statistically significantly larger than those of white subjects (n-weighted mean effect = 0.556 +/- 0.142 S.E., n = 5). Further, the meta-analysis of various racial populations from five studies shows that males have significantly larger discs than females (n-weighted mean effect = 0.151 +/- .055 S.E., n = 9). CONCLUSION: Different machines and techniques give different results when populations of similar racial composition are measured. We recommend applying the above normalizing factors when comparing studies that employ different instruments.     

What can we learn from the disc appearance about the risk factors in glaucoma?

The author has been involved in 3 studies, the multicentre collaborative normal-tension glaucoma study, a study of 4 phenotypes of glaucomatous disc appearances and their associations, and a study reporting on biostatistical evidence for 2 distinct chronic open-angle glaucoma populations. These studies have some common threads whose clinical implications are discussed.     

【In Press】 Optic disc and peripapillary changes by optic coherence tomography in high myopia

Myopia, a worldwide condition, is a multifactorial disease resulting in many ocular complications. Early onset of myopia has a great tendency to develop high myopia and pathological myopia later in life. The pathophysiology and progression of myopia is still unclear. Owing to its involving in visual function, optic disc and peripapillary change in high myopia can''t be neglected, and it may help in better understanding of the pathophysiology or mechanism of myopia progression. Recently, advanced imaging techniques have been developed, such as optical coherence tomography (OCT), allowing for better detecting of optic disc and peripapillary change. OCT is a high-resolution and noninvasive measurement for detection of ocular structure. Herein, we provide an updated review of optic disc and peripapillary change in OCT image, including its characteristics and clinical significance. We also propose some problems needed further investigation.     

Duplication of the optic disc: true or pseudo? A coloboma or not a coloboma?

PURPOSE: To present an unusual case of optic disc pseudoduplication with colobomata. METHODS: Clinical evaluation, fundus photography and literature review. RESULTS: Optic disc duplication is a rare clinical entity. CONCLUSIONS: We report what we believe to be the first case of pseudoduplication of the optic disc with coexistent bilateral optic disc colobomata.