Advanced visual field loss secondary to optic nerve head drusen: Case report and literature review

BackgroundOptic nerve head drusen (ONHD) is a relatively uncommon condition that results from calcific degeneration of axons within the optic nerve. The abnormal drusen bodies can enlarge, compressing normal nerve structures, and ultimately may result in vision loss. Drusen often are discovered through clinical evaluation with a dilated funduscopic examination. Ancillary testing, including computed tomographic (CT) imaging, B-scan ultrasonography, autofluorescence imaging, nerve fiber layer imaging, and threshold visual field evaluation are helpful to confirm the existence of ONHD and to evaluate for progression of this condition.Case reportThis case report discusses the clinical presentation of a patient with advanced visual field loss from ONHD and the ancillary testing used to confirm the diagnosis. A complete review of literature on ONHD is discussed.ConclusionsCurrently, there is no cure or direct treatment for progressive vision loss or complications that may develop from ONHD. Useful diagnostic tools include serial automated threshold visual fields, nerve fiber layer analysis, and fundus photography. It is suggested that ocular hypotensive agents be used to lower intraocular pressure prophylactically to prevent further nerve fiber layer and optic nerve damage.     

Optic nerve head drusen and visual field loss in normotensive and hypertensive eyes

OBJECTIVE: To compare visual field loss (VFL) in eyes with optic nerve head drusen (ONHD) with or without ocular hypertension (OHT). METHODS: The records of all patients aged 45 years or older with a diagnosis of ONHD at 2 centers were reviewed. OHT was defined as intraocular pressure >or=22 mm Hg. We categorized ONHD into 3 grades based on visibility on disc photographs. RESULTS: We identified 22 eyes (13 patients) with both ONHD and OHT and 81 normotensive eyes (47 patients) with ONHD. VFL was present in 20/22 (90.9%) of hypertensive eyes compared with 54/81 (66.7%) of normotensive eyes (P=0.03, Fisher exact test). Drusen grade III and OHT were both independently and significantly associated with greater incidence of VFL (logistic regression analysis). CONCLUSIONS: VFL occurs more frequently in eyes with ONHD that also have OHT. Eyes with grade III ONHD are at increased risk for VFL compared to eyes with grade I drusen with the same intraocular pressure status. Patients with OHT and ONHD should undergo close surveillance for disease progression and be treated appropriately to prevent additional VFL.     

Relationship between optic nerve head microcirculation and visual field loss in glaucoma

PURPOSE: To study the relationship between optic nerve head blood flow velocity and visual field loss in patients with primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). METHODS: This study included 44 eyes of 44 patients with POAG and 44 eyes of 44 patients with NTG. To evaluate optic nerve head blood flow velocity, the square blur rate (SBR) was measured by means of laser speckle flowgraphy. The correlation between SBR and Humphrey visual field indices was evaluated with linear regression analysis. RESULTS: In the NTG group, the average SBR at the superior and inferior temporal neuroretinal rim was positively correlated with mean deviation (MD) (r = 0.349, p = 0.020). The SBR at the superior or inferior temporal neuroretinal rim was positively correlated with the sum of the total deviations in the corresponding hemifields (r = 0.299, p = 0.049; r = 0.354, p = 0.019, respectively). The correlations between SBR and MD did not differ statistically between the NTG and POAG groups; however, no significant correlation between SBR and visual field indices was observed in the POAG group. CONCLUSION: These results suggested that the change in the circulation of the optic nerve head may be related to visual field damage in the NTG group but may be less involved in visual field damage in the POAG group.     

Pulfrich's phenomenon and drusen of optic nerve head

The comportment of placing a swinging pendulum (Pulfrich's phenomenon) in front of three cases of optic nerve head drusen has shown that reduced conductivity is a fact in the optic nerve harboring the drusen, giving oval circular movement. A suggestion is made to use this simple test in patients with this disease.     

Scleral canal size and optic nerve head drusen

From projected optic disk photographs we measured the size of the scleral canal in two samples of emmetropic patients: one of patients with unilateral pseudopapilledema and drusen and the other of the general normal population. Measurements on the non-drusen-containing optic disk of patients with unilateral drusen were taken to reflect the scleral canal size of the fellow, affected eye. For both trained (t = 6.642) and untrained (t = 4.274) observers, the average diameters of the non-drusen-containing optic disks of patients with unilateral drusen were significantly smaller than those of the optic disks of normal patients (P = .0005, one-tailed independent t-test). The association of a small scleral canal with vascular anomalies, frequently noted in optic disks of patients with drusen, indicates a mesodermal dysgenesis of the optic nerve head.     

Two differing presentations of optic nerve head drusen.

BACKGROUND: Optic nerve head drusen was recognized histologically in 1858 by Heinrich Muller The majority of optic nerve head drusen cases have been benign in nature. However, optic nerve head drusen can be visually devastating. CASE REPORTS: Two patients were diagnosed with optic nerve head drusen. They were similar in age and each had a best-corrected visual acuity of 20/20 OU. Although the diagnosis was the same, the disease affected each person very differently. One is currently asymptomatic; the other is legally blind secondary to severely constricted visual fields. These cases demonstrate the diversity of visual effects produced by optic nerve head drusen. Appropriate ocular workup, including visual fields, B-scan ultrasonography, computed tomography, and other tests, are presented. CONCLUSION: There is no existing treatment for optic nerve head drusen. Proper diagnosis and patient education is the best-available modality of care. Patients need to be aware of potential complications which, while rare, can affect vision. Visual-field testing can aid in monitoring for subtle changes in vision.     

Predictive factors of the optic nerve head for development or progression of glaucomatous visual field loss

PURPOSE: To evaluate which morphologic features of the optic disc are predictive factors for the development or progression of visual field loss in chronic open-angle glaucoma. METHODS: The prospective observational clinical study included 763 eyes of 416 white subjects with ocular hypertension and chronic open-angle glaucoma. During the follow-up time (mean, 67.4 months; median, 65.1; range, 6.2-104.5), all patients underwent repeated qualitative and morphometric evaluation of color stereo optic disc photographs and white-on-white visual field examination. Progression of glaucomatous visual field damage was defined by point-wise regression analysis for each of the 59 locations in the visual field. Outcome measures were qualitative and quantitative morphologic optic nerve head parameters. RESULTS: Development or progression of glaucomatous visual field defects was detected in 106 (13.9%) eyes. At baseline of the study, neuroretinal rim area was significantly (P < 0.002) smaller, the beta zone of parapapillary atrophy (P < 0.003, nasal sector) was significantly larger, and age was significantly higher (P < 0.003) in the progressive study group than in the nonprogressive study group. Both study groups did not vary significantly in size of the optic disc and the alpha zone of parapapillary atrophy. Cox proportional hazard regression analysis revealed that the progression of glaucomatous visual field loss depended significantly on the area of the neuroretinal rim (P < 0.001) and age (P < 0.001), but was independent of diameter of the retinal arterioles and veins. CONCLUSIONS: Morphologic predictive factors for development or progression of glaucomatous visual field defects in whites are small neuroretinal rim area and large beta zone of parapapillary atrophy. Age is an additional nonmorphologic parameter. Progression of glaucomatous optic nerve head changes is independent of the size of the optic disc and alpha-zone of parapapillary atrophy and retinal vessel diameter.     

The relationship between the visual field and the optic nerve head in glaucomas

In a retrospective study of 50 eyes with chronic open-angle glaucoma we compared the findings obtained using stereochronoscopy (Sc), papillometry (Pm) and visual-field measurements. We found relationship between the neuroretinal-rim area and the visual-field findings measured using the Octopus glaucoma program, G1. There was only a weak relationship between the Sc findings and the visual-field measurements. This suggests that Sc detects a type of damage that is not detectable either using Pm or by visual-field examinations. Our results also suggest that quantitative perimetry detects the same kind of damage as that revealed by Pm. The neuroretinal-rim area was best correlated with short-term fluctuation, but was also very significantly correlated with mean damage and corrected loss variance.Supported in part by the Swiss National Fund (3.970-0.84)     

The investigation of retinal nerve fiber layer thickness in eyes with optic nerve head drusen

Purpose: To investigate the effect of optic nerve head drusen (ONHD) on the retinal nerve fiber layer (RNFL) thickness. Patients and methods: Twenty-one nonglaucomatous eyes with various degrees of ONHD and 27 age-matched control eyes were included in the study. Visual fields and RNFL thickness were assessed using Humphrey field analyzer and optical coherence tomography (OCT), respectively. The eyes with various degrees of ONHD and the control eyes were compared with regard to visual field (VF) indices and RNFL thicknesses. Results: VF indices of the eyes with ONHD were significantly different from those of the control eyes (p < 0.05), but no significant difference existed among the eyes with various degrees of ONHD (p > 0.05). The RNFL thicknesses of inferior quadrants of the eyes with ONHD were significantly thinner than those of the control eyes (p < 0.05). A significant thinning of the RNFL in the superior and nasal quadrants was observed in grade II and III discs, while temporal quadrants only in grade III discs presented a similar change (p < 0.05). A comparison between the RNFL thicknesses of various degrees of ONHD did not show a significant statistical difference (p > 0.05) except for the thickness in the temporal RNFL (p < 0.05). Conclusion: We found a significant decrease in the RNFL thickness of ONHD patients compared to that of the control subjects. The measurements of VF indices did not show a significant difference between various degrees of ONHD. In contrast, RNFL thickness was significantly correlated with the amount of ONHD. This suggests that OCT may allow the detection of early changes in RNFL thickness in ONHD patients before observable changes in the visual field are seen.     

Histologic findings after surgical excision of optic nerve head drusen

PURPOSE: To report the histopathologic findings of a case of bilateral massive optic nerve head (ONH) drusen. METHODS: A 59-year-old man presented with bilateral massive ONH drusen and secondary compromise of the retinal vasculature leading to vision of counting fingers at 1 ft in the left eye and 20/30 in the right eye. The inferior one half of the left ONH druse was excised resulting in no light perception vision postoperatively. RESULTS: Energy-dispersive spectroscopy suggested the composition of the ONH druse to be calcium phosphate (Ca3[PO4]2), which has implications on pathogenesis of neuronal cell death in ONH drusen. Scanning electron microscopy demonstrated embedded metal particles, likely to be remnants of the instruments used. CONCLUSION: Massive ONH drusen are actually one large druse that has multiple excrescences on its surface giving it the variegated appearance. Although surgical excision of ONH drusen may be technically possible, consideration should be given to improvements in instrumentation and patient selection criteria.     

Optic nerve head drusen associated with abnormally small optic discs

Summary Using Littmann's method for correcting the magnification of central fundus photographs we evaluated the absolute optic disc size in 26 eyes with visible optic nerve head drusen. The optic nerve head area in these eyes (1.79 + –0.50mm²) was significantly smaller (p<0.001) than normal standard values previously determined (2.89 + –0.76 mm²). The drusen were most commonly located and most densely packed at the upper and lower optic disc border. The coefficients of variation of the method's reproducibility were 0.06 for intraobserver and 0.11 for interobserver determination.The abnormally small optic disc indicating an abnormally small optic nerve scleral canal may inhibit by mechanical compression the axonal flow within the optic nerve fibers. This may ultimately lead to drusen formation. Pseudoneuritis also associated with an abnormally small optic disc may be a preceder of acquired optic nerve head drusen.This study was supported in part by the Deutsche Forschungsgemeinschaft, grant Nr. NA/55-4/1.     

Correlation of optic nerve head tomography with visual field sensitivity in papilledema

PURPOSE: To quantify the relationship between optic nerve head tomography and perimetric sensitivity in patients with papilledema. METHODS: Eight patients with variable degrees of recently diagnosed papilledema associated with idiopathic intracranial hypertension (IIH) were evaluated with confocal scanning laser ophthalmoscopy (CSLO) and automated perimetry. Patients were followed up with serial measurements over a period of 5 to 30 months (mean +/- SD, 17.1 +/- 9), while under medical treatment (acetazolamide). The tomographic parameters, volume above reference (VAR), volume above surface (VAS), effective mean height (EMH), and maximum height in contour (MxHC), were obtained by tomography, either globally or from predefined disc sectors. The perimetric indices, mean deviation (MD) and pattern SD (PSD), were evaluated. The results from patients' right eyes and the individual intereye differences in both tomographic and perimetric parameters, were statistically evaluated by nonparametric correlational (Spearman) and repeated measures (Wilcoxon) analyses. RESULTS: At baseline, all tomographic parameters were negatively correlated with MD in global (r = -0.8) and sectorial (r = -0.6) evaluations. The interocular differences in overall tomographic parameters were correlated with corresponding differences in perimetric MD (r = -0.8) and PSD (r = 0.6). During the follow-up period, volumetric disc parameters decreased (P < 0.02), whereas perimetric MD increased (P = 0.02) at comparable times. CONCLUSIONS: In patients with recently diagnosed papilledema, optic nerve head tomographic abnormalities are quantitatively correlated with visual field sensitivity losses. Therapeutic improvement of volumetric parameters may be paralleled by recovery in perimetric sensitivity. The data support the possible use of both techniques in combination to monitor the amount of papilledema and the effectiveness of treatments designed to reduce intracranial hypertension.     

Afferent pupillary defect associated with optic nerve head drusen.

BACKGROUND: Optic nerve head drusen (ONHD) are a relatively uncommon finding with an estimated prevalence of anywhere from 0.3% to 2%. Reports of relative afferent pupillary defects (RAPDs) associated with ONHD are scarce. CASE REPORT: A patient with an RAPD was found to have ONHD as the only apparent etiology of the RAPD. The various diagnostic tests relevant to the case, the differential diagnosis, and the pathological features of ONHD are discussed. CONCLUSIONS: It is important for the clinician to consider an RAPD as a possible pathological feature of ONHD--especially with an asymmetric presentation.     

Laser scotometry in drusen and pits of the optic nerve head

Laser scotometry is an accurate means of detecting dense blind spots. A small low-energy spot is guided across the fundus from nonseeing to seeing areas. Patient responses are recorded on fundus photographys, allowing direct correlation with fundus pathology. Accuracy to less than 1 degree is feasible. All typical optic nerve drusen tested with this technique had field defects. In cases of optic nerve pits, dense scotomas correlated with the shape of visible nerve fiber defects rather than with the shape of serous retinal detachments.