Small Optic Nerve Head Research Articles

Role of Optic Nerve Head Characteristics in Predicting Intraocular Pressure Spikes after Cataract Surgery in Highly Myopic Eyes.

To evaluate the characteristics of optic nerve head (ONH) in highly myopic eyes and its role in predicting intraocular pressure (IOP) spikes after cataract surgery. Patients who are highly myopic andwere scheduled for cataract surgery were enrolled in this prospective case series study. IOP was measured preoperatively and at 1day and 3days postoperatively. ONH characteristics including area, tilt ratio, lamina cribrosa (LC) thickness, and depth, and the presence of LC defects were evaluated with enhanced depth imaging optical coherence tomography. Factors influencing LC defects and early IOP spike were investigated using multivariate stepwise logistic regression. In total, 200 highly myopic eyes of 200 patients were analyzed: 35.00% had small ONH, 53.00% had ONH tilt, and 14.00% had LC defects. Multivariate analysis demonstrated female patients with larger ONH area and deeper LC tended to have LC defects (all P < 0.05). As to postoperative IOP, IOP change, and incidence of IOP spikes, eyes with small ONH, ONH tilt, and LC defects had similar (all P > 0.05), higher (all P < 0.05), and lower (all P < 0.05) outcomes compared with those without the corresponding characteristic, respectively. Multivariate analysis showed that presence of LC defects and thicker LC were protective factors for early IOP spikes, and axial length > 28mm was a risk factor (all P < 0.05). Female patients with larger ONH area and deeper LC tend to have LC defects, which, together with thicker LC, was correlated with less IOP spikes in highly myopic eyes. This study was conducted as part of a larger project, the Shanghai High Myopia Study, registered at www. gov (accession number NCT03062085).

Evaluation of optic nerve head in patients with small optic disc using oral isotretinoin

BackgroundIsotretinoin has a number of neurological and ocular side effects, but its effect on the optic nerve has not been demonstrated. PurposeTo investigate the effect of oral isotretinoin therapy on the peripapillary retinal nerve fibre layer thickness (RNFL) in patients with small optic disc area using optical coherence tomography (OCT). MethodsThis retrospective study included 55 patients taking 40 mg/day oral isotretinoin. The patients were grouped according to optic disc area. Patients with small optic disc area were included in group 1 and the others in group 2. RNFL thickness was measured by spectral domain OCT before the treatment, at the third month of the treatment, and at the third month after treatment. ResultsRNFL increased significantly in group1 in the third month of treatment compared to that before the treatment (P < 0.001); no significant change was observed in group 2 (P < 0.244). DiscussionOral isotretinoin treatment may be effective in patients with small optic nerve head. The presence of a small optic disc may increase the risk of adverse effects such as decreased dark adaptation, reduced vision, headache, or photophobia. ConclusionEvaluating the optic disc size before initiation of oral isotretinoin treatment may assist in planning patient treatment.

Caractéristiques de la papille chez les sujets glaucomateux et normaux à l’OCT dans une population Noire Africaine

To determine the correlations between the size of the optic disc and glaucomatous defects in black Africans. Retrospective observational study. The study was conducted over a two-year period from November 2014 to October 2016, based on records of black Togolese patients who had undergone optic nerve head (ONH) OCT or ganglion cell complex OCT for assessment of glaucoma. The population was divided into 3 groups (I, II and III) depending on the size of the ONH. The ONH was considered small (Group I) if its size was less than the mean -1 SD, medium (Group II) if its size was within 1 SD of the mean, and large (Group III) if its size was greater than the mean+1 SD. Glaucomatous lesions were qualitatively identified on RNFL and or GCC. The ONH parameters were compared in the 3 groups. The Chi-square test was used to compare the percentages, and the t test to compare the means with statistical significance of 5%. The Pearson correlation coefficient (r2) was used to measure correlations. A total of 586 eyes of 298 patients were examined, 314 glaucomatous eyes and 272 healthy eyes. The mean age was 41.0±15.7 [6; 86] years. There were 159 men vs. 137 women, with a sex ratio of 1.2. The mean surface area of the ONH was 2.80±0.55mm2. Small ONH's (Group I) were defined as a surface area of less than 2.25mm2, medium-sized ONH's (Group II) as an area between 2.25 and 3.35mm2 and large ONH's (Group III) as an area greater than 3.35mm2. Small ONH's represented 14.7%, (86 eyes), medium-sized 68.6% (408 eyes) and large ONH's 16.8% (98 eyes). The mean surface area of the neuroretinal rim, cup, the cup-disc ratio and the RNFL thickness were statistically significant in the 3 groups. Similarly, all these parameters were significant in groups of glaucomatous or non-glaucomatous eyes, except for the surface area of the cup. The RNFL thickness was weakly correlated with the surface area of the ONH (r2=0.39), moderately correlated with the surface area of the neuroretinal rim (r2=0.57). The surface area of the ONH was strongly correlated with the surface area of the cup (r2=0.7). The neuroretinal rim surface area was strongly correlated with the cup-disc ratio (r2=0.66). The size of the ONH was correlated with the size of the cup, but it was not correlated to the surface area of the neuroretinal rim or the thickness of the nerve fibers. Analysis of the RNFL and GCC is essential for the diagnosis, especially in the case of large ONH's.

Optic Nerve Head Drusen Prevalence and Associated Factors in Clinically Normal Subjects Measured Using Optical Coherence Tomography

To investigate the prevalence of optic nerve head drusen (ONHD) in clinically normal subjects using enhanced depth imaging (EDI) optical coherence tomography (OCT) and to evaluate associated factors. Prospective, cross-sectional, observational study. Total of 130 clinically normal subjects. Serial horizontal and vertical EDI OCT B-scans (interval between scans, ∼30 μm) of the optic nerve head (ONH) were obtained in both eyes of clinically normal subjects. Signs of ONHD were defined as horizontal hyperreflective bands perpendicular to the OCT beam with or without a signal-poor core. The minimum length of isolated hyperreflective bands was determined based on analysis of 34 eyes with clinically definite ONHD. Age, gender, ONH diameter, and axial length were obtained from participants. Prevalence of ONHD in clinically normal subjects and its association with age, gender, ONH diameter, and axial length. Based on the measurements of 94 isolated hyperreflective bands in the 34 eyes with clinically definite ONHD, the minimum length of isolated hyperreflective ONHD bands in clinically normal subjects was set as 45 μm (mean minus 2 standard deviations). Among 260 clinically normal eyes (130 subjects; 68 women; mean age, 40±17 years), EDI OCT was positive for horizontal hyperreflective ONHD bands in 28 eyes (10.8%) of 19 subjects (14.6%). Of these 28 eyes, 25 eyes (9.6% of total 260 eyes) of 16 subjects (12.3% of total 130 subjects) showed isolated hyperreflective bands with no signal-poor core, and 3 eyes (1.2% of total 260 eyes) of 3 subjects (2.3% of total 130 subjects) showed a signal-poor core surrounded by hyperreflective bands. No significant differences were found in mean age (44 vs. 39 years; P= 0.121) or gender distribution (56% vs. 52% female; P= 0.766) between clinically normal subjects with hyperreflective ONHD bands and those without. Logistic regression analysis showed that a decrease in ONH diameter by 100 μm and axial length by 1 mm increased the odds of ONHD presence by 1.5-fold (odds ratio [OR]= 1.56 [confidence interval (CI), 1.22-2.00]; P < 0.001) and 2-fold (OR= 2.00 [CI, 1.15-3.49]; P= 0.015), respectively. Subclinical ONHD may be more prevalent than previously believed. Significant associations of subclinical ONHD with smaller ONH and shorter axial length were found.

Retinal Nerve Fiber Layer Thicknesses in Three Different Optic Nerve Head Size Groups Measured by Cirrus Spectral Domain Optical Coherence Tomography

Objectives:To compare the retinal nerve fiber layer (RNFL) thicknesses in three different optic nerve head (ONH) size groups measured by Cirrus spectral domain optical coherence tomography (OCT).Materials and Methods:Between January and March 2013, 253 eyes of 253 healthy subjects were enrolled in this study (mean age: 42.7±7.4 years [28-62 years]; 121 men and 132 women). The patients were divided into 3 groups according to ONH size: 77 patients in the “small ONH” group (ONH area <1.63 mm2), 90 patients in the “medium ONH” group (ONH area 1.63-1.97 mm2), and 86 patients in the “large ONH” group (ONH area >1.97 mm2).Results:There were significant differences in superior (p=0.008), inferior (p=0.004) and average RNFL thickness (p=0.001) between the small, medium and large ONH groups. Positive correlations between ONH size and inferior/average RNFL thicknesses were significant but very weak (r=0.150, p=0.017 and r=0.157, p=0.013 respectively).Conclusion:RNFL thickness as measured by Cirrus OCT is positively correlated with ONH size and the differences in RNFL thickness were statistically significant between groups. This correlation and difference may be the result of a varying distance between the circular scan and the ONH margin.

Retinal Nerve Fiber Layer Thickness in Dominant Optic Atrophy: Measurements by Optical Coherence Tomography and Correlation with Age

To measure the retinal nerve fiber layer (RNFL) thickness by means of optical coherence tomography (OCT) in patients with dominant optic atrophy (DOA). Cross-sectional study. Thirty-three patients from 15 pedigrees with DOA harboring heterozygous mutations in the OPA1 gene and 43 healthy subjects were enrolled. The RNFLs of DOA patients were studied by OCT and compared with those of 43 healthy subjects matched for age and optic nerve head (ONH) size. Retinal nerve fiber layer thickness. Dominant optic atrophy patients revealed a significant RNFL thickness reduction in all quadrants, with a preferential involvement of the temporal and inferior sectors. The progressive decline of RNFL thickness with age was similar to that observed in healthy subjects and was more evident in the 2 quadrants with higher residual amounts of fibers, that is, the superior and the inferior. The temporal quadrant was profoundly depleted of fiber so that the further rate of loss of microns per year is close to zero, whereas the nasal quadrant was spared the most by neurodegeneration. The present findings, taken in conjunction with the authors' previous description of small ONH size in DOA, strongly suggest that patients with this disease are born with fewer optic nerve axons and support the hypothesis that subsequent visual loss depends on further age-related loss of fibers, which also occurs in controls. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Clinical assessment of the optic disc at risk of nonarteritic anterior ischaemic optic neuropathy

Editor, Nonarteritic anterior ischaemic optic neuropathy (NAION) is an acute optic neuropathy occurring predominantly in small optic nerve heads in elderly patients (Beck et al. 1984; Hayreh et al. 1994; Hayreh 1996; Jonas & Xu 1993). Recently, phosphodiesterase-5 inhibitor drugs such as sildenafil have been mentioned as a potential risk factor for NAION (Pomeranz & Bhavsar 2005; Hayreh 2008). If indeed the intake of phosphodiesterase-5 inhibitor drugs is a risk factor for NAION, the detection of subjects at risk of the development of NAION prior to the intake of the drugs may be helpful to give a warning not to use the medication. Subjects at risk of NAION may be detected by an ophthalmoscopic exa-mination searching for subjects with a small optic nerve head. Because the assessment of the optic nerve head and the detection of discs at risk of NAION are markedly dependent on the examiner, we performed this study to assess the inter-observer variability in the ophthalmoscopic examination of the optic nerve head in classifying risk of NAION. The clinical observational study included monoscopic optic disc photographs of 40 healthy eyes of Caucasian subjects without any health problems. The horizontal cup/disc diameter ratio as measured on the photographs was 0.48 ± 0.11 (mean ± standard deviation) (median: 0.50; range: 0.18–0.76). The optic disc photographs were presented to three groups of examiners. The first group consisted of 10 experts in the field of neuro-ophthalmology. The second group included 16 comprehensive ophthalmologists who had been working in private office for at least 10 years. The third group included 35 residents in ophthalmic training with an experience in ophthalmology ranging between 1 and 5 years. All examiners were asked to assess whether the optic disc represented a risk of the development of NAION. Before the test, the association between a small optic disc with a slightly unsharp optic disc border and NAION was discussed. The 10 experts showed a relatively high degree of agreement of about 80% in classifying the discs with a cup/disc diameter ratio of 0.40 or less for NAION (Table 1). In a corollary way, they showed a relatively high degree of agreement of about 80% in classifying discs with a cup/disc diameter of 0.56 or higher as not at risk of NAION. For the intermediate discs with a cup/disc diameter ratio ranging between 0.40 and 0.55, the agreement rate was roughly 60%. For the 16 practitioners when compared with the experts, the agreement was generally lower and did not vary significantly (p > 0.05) from the agreement rate of the residents (Table 1) (Fig. 1). Scattergram showing the distribution of the agreement (percentage of yes-answers) among 16 ophthalmologists in private practice in classifying optic nerve heads as discs at risk of nonarteritic anterior ischaemic optic neuropathy (NAION), in relation to the horizontal cup/disc diameter ratio. The scattergram shows a wide variation in the decision, whether the individual eye had an optic disc at risk of NAION. The results suggest that ophthalmologists in private practice and ophthalmic residents show a relatively high inter-observer variability in classifying optic nerve heads as discs at risk of the development of NAION. Potential limitations of our study should be mentioned. The artificial examination conditions for the study participants who knew that they were tested may have led to an increased concentration of the study participants and to falsely good results. Another limitation of the study may be the term ‘disc at risk’ itself. According to Hayreh, it is not the small disc that poses the risk to develop NAION, but instead it may be a drop in arterial blood pressure, occurring mostly at night (Hayreh et al. 1994; Hayreh 1996). This drop in blood pressure leads to an initially circumscribed ischaemic event in the optic nerve head. Because of the lack of space in small discs, this normally unremarkable event may trigger a vicious circle with an ischaemic oedema-induced compression of the tissue in the vicinity of the circumscribed malperfusion, progressively increasing the regional ischaemia. In conclusion, the diagnostic precision of ophthalmologists in detecting an optic disc at risk of NAION may not be sufficient to reliably counsel a subject about the risk of NAION. Supported by the Paul and Evanina Bell Mackall Foundation, a Senior Scientist Award (AML) and an unrestricted grant from Research to Prevent Blindness Inc. and a grant-in-aid from Pfizer Inc.

Anterior ischemic optic neuropathy associated with Vogt–Koyanagi–Harada disease

Optic disc swelling is a common finding associated with Vogt-Koyanagi-Harada disease (VKH); however, visual field loss from optic disc involvement is uncommon. This reports report presents recent findings regarding unusual patients with visual field defects from optic disc involvement, thus suggesting the presence of anterior ischemic optic neuropathy (AION) in the acute phase of VKH. Observational case series. A consecutive series of 52 patients with VKH (6 complete VKH, 46 incomplete VKH) was reviewed. Fifteen patients in this series had optic disc swelling, and six of them developed irreversible visual field defects in the acute phase of VKH. The clinical features of these six patients were analyzed. The patients with associated visual field loss were four males and two females between 54 to 79 years of age. They had bilateral panuveitis associated with meningismus. All of the patients had bilateral optic disc swelling and fluorescein angiography showed both a filling delay and late leakage of the optic disc. Visual field examinations revealed various degrees of visual field defects in 11 eyes. They were treated with high-dose corticosteroid therapy, and several weeks later, both the uveal inflammation and optic disc swelling disappeared. The visual fields showed some improvement as the retinal detachments and disc swelling resolved, but the visual field defects remained in ten eyes. The small and localized visual field defects were asymptomatic. Subsequently, optic disc pallor developed in nine eyes and retinal nerve fiber layer thickness, measured by optical coherence tomography, was decreased in six eyes. The fundus gradually showed various degrees of hypopigmentation, but did not show any chorioretinal atrophy causing visual field loss. Four patients had risk factors for AION, including diabetes mellitus or a relatively small optic nerve head. In this consecutive series of patients with VKH, 15 out of 52 patients were found to have disc swelling, and six patients, who were mostly elderly, had associated visual field loss, which is probably due to AION associated with VKH.

Superior segmental optic nerve hypoplasia: The topless disc syndrome

Background Optic nerve hypoplasia is a well-known congenital maldevelopment presenting with an abnormally small optic nerve head occupying the central aspect of a normally sized chorioscleral canal. Characteristically, the optic nerve head is surrounded by scleral anlage with a “double ring sign.” Less commonly appreciated, however, is the fact that optic nerve hypoplasia may be sectorial rather than total and involving only the superior aspect of the optic disc with corresponding inferior visual field loss. Case Report A 51-year-old woman presented with a previous diagnosis of idiopathic optic atrophy superiorly in the left eye. Detailed observation revealed that the disc was not atrophic superiorly but actually hypoplastic, and the patient received a conclusive diagnosis of superior segmental optic nerve hypoplasia. Conclusions It must be appreciated that optic nerve hypoplasia can also affect solely the superior aspect of the disc with subsequent functional deficits. It is important to differentiate this syndrome from true optic atrophy to ensure proper management.

Heidelberg retina tomograph parameters of the optic disc in eyes with progressive retinal nerve fibre layer defects

To determine the Heidelberg retina tomograph (HRT) parameters that identify glaucomatous changes in optic nerve head (ONH) topography associated with progression of retinal nerve fibre layer (RNFL) defects. A total of 68 eyes with open-angle glaucoma were included in this retrospective study: 34 eyes showed progression of an RNFL defect during the follow-up period and 34 eyes did not. Successful RNFL photographs and scanning laser tomography examinations with the HRT were taken in all patients at each of three visits. The change in HRT parameter values during follow-up was calculated. Progression of the RNFL defect was statistically significantly correlated (p = 0.049) with only one topographic ONH parameter, the cup shape measure. The best combination of two parameters (p = 0.009) included the maximum cup depth and the linear cup : disc area ratio; the best combination of three parameters (p = 0.007) included the maximum cup depth, the linear cup : disc area ratio and the horizontal cup : disc area ratio. Sensitivity and specificity values were 52.9% and 73.5%, respectively, for the cup shape measure, 70.6% and 73.5%, respectively, for the two-parameter combination, and 76.5% and 79.4%, respectively, for the three-parameter combination. The areas under the receiver operating characteristic curve were 0.617, 0.724 and 0.753, respectively. The results indicate that the HRT parameters may be used to detect small ONH changes associated with progression of the RNFL defect. With the exception of the cup shape measure, the parameters which provide the best correlation with progression differ from those considered optimal for recognizing the presence or absence of glaucoma.

Value of the Heidelberg Retinal Tomograph in Optic Nerve Hypoplasia

A case of optic nerve hypoplasia (ONH) is reported to demonstrate the value of the Heidelberg Retinal Tomograph II (HRT) in assisting with the diagnosis. An 8-year-old black male was referred to our clinic for evaluation of right esotropia and presumed amblyopia. Best-corrected visual acuities were 20/60 OD (right eye) and 20/25 OS (left eye). Cover test showed constant right esotropia, measuring 10 at distance and 16 at near. A smaller optic nerve head was detected OD with absence of the double ring sign. The findings of HRT were consistent with a diagnosis of unilateral ONH, with a disc area of 1.545 mm OD vs. 2.527 mm OS. The clinical features, management, and associations of ONH are discussed. HRT is a useful tool to assist in diagnosis of ONH by physically measuring the optic nerve.

Phänotyp des visuellen Systems bei okulokutanem und okulärem Albinismus

In spite of albinism being one of the visual impairments which has been known for over a century, it has only been known for a few decades that albinism is correlated to severe cerebral morphological developmental alterations. The increasing knowledge about the role of melanin in the development and orientation of cerebral neurons not only renders more insight into albinism, but also a greater insight in the physiological neuronal and cerebral development in man. Concerning the morphological and visual phenotype there are new clinical findings which enlarge the known spectrum of albinism. In a representative group of 506 persons with oculocutaneous and ocular albinism who are in care at the Department of Ophthalmology at the University of Saarland (UKS), we present a staging of morphological findings of the iris, retinal pigment epithelium and macula, and of the optic nerve head which has been in use for 10 years. Albinism may present with a remarkably mild ocular phenotype and a near to normal functional phenotype. We present correlations between molecular genetic types of albinism, ocular phenotype and visual function. Of great importance concerning later visual acuity is the dysplasia of the optic nerve head (ONH), which is a frequent finding in albinism. The appearance of the ONH should always be included in any clinical description of an albinism patient. It is highly possible that due to a moderate phenotype there are still many patients who have not been diagnosed yet. Visual acuity of 30/20 to 20/20 and no nystagmus do not rule out albinism. In addition, when performing albino VEPs in phenotypically normal children with infantile strabismus, small ONHs, but normal visual acuity and no nystagmus, the classical atypical chiasmal crossing is sometimes found. Therefore, the number of persons having undiagnosed albinism is probably quite high, perhaps there even is a very broad transition zone from normal to albinotic.

Optic disc size and optic nerve damage in normal pressure glaucoma.

Recent reports indicate that eyes with normal pressure glaucoma have larger optic discs than eyes with primary open angle glaucoma or normal eyes. This study was performed to find whether, in normal pressure glaucoma, a large disc is associated with more optic nerve damage than a small disc. Colour optic disc photographs of 74 patients with normal pressure glaucoma were assessed morphometrically. Taking the study group as a whole, the optic disc size decreased significantly (p = 0.04) with increasing visual field defect. In an intraindividual bilateral comparison, the side differences in the disc area of the right minus the left eye of the same individual were not significantly correlated with the side differences in the mean visual field defect. The results indicate that the eye with the larger optic disc, when compared with the contralateral eye with the smaller optic nerve head, showed neither a significantly more marked nor less pronounced glaucomatous optic nerve damage. It suggests that for a given patient the degree of glaucomatous optic nerve atrophy was not markedly associated with the optic disc size. The finding that patients with large visual field defects had smaller discs than patients with moderate perimetric loss may indicate that the results of previous cross sectional studies reporting on an unusually large disc size in normal pressure glaucoma may be due partially to selection.

Optic Disk Risk Factors for Nonarteritic Anterior Ischemic Optic Neuropathy

The anatomic characteristics of a relatively small optic nerve head, absent to small physiologic cup, abnormal branching pattern of central retinal vessels, and a lush nerve-fiber bundle layer elevating the disk margins are associated with the occurrence of certain ischemic disease states. These diseases include the following: (1) nonarteritic anterior ischemic optic neuropathy, (2) anterior ischemic optic neuropathy of the young, (3) the papillopathy in patients with juvenile insulin-dependent diabetes mellitus, and (4) Leber's hereditary optic neuropathy. The finding of such a disk at risk should signal the possible later development of visual dysfunction. Ordinarily, when an ophthalmologist discusses risk factors in relationship to the optic disk, the topic is that of open-angle glaucoma and the predictability of the ultimate development of visual field loss. In the early 1980s, Hoyt suggested that certain disk characteristics may predispose an individual to the development of nonarteritic anterior ischemic optic neuropathy (Hoyt, W. F., unpublished data, presented at the Rocky Mountain Neuro-Ophthalmologic Society Meeting, February 1982). Specifically, in these cases he noted that the unaffected eye has a small or absent physiologic cup. Several investigators went on to confirm Hoyt's observation that these crowded disks are at risk for developing nonarteritic anterior ischemic optic neuropathy.! The hallmarks of the disk at risk are as follows: (1) relatively small optic nerve head, (2) absent to small physiologic cup, (3) increased number of branches of the central retinal vessels within the disk, and (4) a normal, healthy-appearing nerve-fiber bundle layer with heaping up of at least the superior, nasal, and inferior fibers (Fig. 1). These disks are similar in many ways to those described by Rosenberg, Savino, and GlaserS,6 as being characteristic of pseudopapilledema. Presumably, a small physiologic cup is the

Retinal Photoreceptor Count, Retinal Surface Area, and Optic Disc Size in Normal Human Eyes

The optic disc area of normal human eyes shows an interindividual variability of 1:7. This study evaluated whether the variation in the optic nerve head size is correlated with a variability in the retinal photoreceptor count and the retinal surface area. Forty-six normal human donor eyes with an axial length of less than 26 mm were examined. The corneoscleral button, lens, and vitreous body were removed. The remaining cup of the eye was cut into orange slice-like pieces. Up to 25 retinal biopsies were taken from areas arranged in increasing distance from and concentric to the fovea. The photoreceptor outer segments were sonographically removed. The photoreceptor inner segments were counted on photographs taken from the outer side of the retina. The count of the rods (mean +/- standard deviation: 57,447,000 +/- 10,481,000), the count of the cones (3,246,000 +/- 618,000), the optic disc size, and the retinal surface area (1204 +/- 184 mm2) were significantly (P < 0.05) and positively correlated with each other. The results indicate that eyes with large optic nerve heads as compared with eyes with small optic discs may have a higher count of rods and cones and a larger retinal surface area. It corresponds with the positive correlation between the optic nerve fiber count and the optic disc size. Taking into account a loss of photoreceptors in glaucoma as recently reported, it may point toward a higher anatomic reserve capacity in glaucomatous eyes with large optic discs than in eyes with small optic nerve heads.

Optic Disk Risk Factors for Nonarteritic Anterior Ischemic Optic Neuropathy

The anatomic characteristics of a relatively small optic nerve head, absent to small physiologic cup, abnormal branching pattern of central retinal vessels, and a lush nerve-fiber bundle layer elevating the disk margins are associated with the occurrence of certain ischemic disease states. These diseases include the following: (1) nonarteritic anterior ischemic optic neuropathy, (2) anterior ischemic optic neuropathy of the young, (3) the papillopathy in patients with juvenile insulin-dependent diabetes mellitus, and (4) Leber's hereditary optic neuropathy. The finding of such a disk at risk should signal the possible later development of visual dysfunction. Ordinarily, when an ophthalmologist discusses risk factors in relationship to the optic disk, the topic is that of open-angle glaucoma and the predictability of the ultimate development of visual field loss. In the early 1980s, Hoyt suggested that certain disk characteristics may predispose an individual to the development of nonarteritic anterior ischemic optic neuropathy (Hoyt, W. F., unpublished data, presented at the Rocky Mountain Neuro-Ophthalmologic Society Meeting, February 1982). Specifically, in these cases he noted that the unaffected eye has a small or absent physiologic cup. Several investigators went on to confirm Hoyt's observation that these crowded disks are at risk for developing nonarteritic anterior ischemic optic neuropathy.! The hallmarks of the disk at risk are as follows: (1) relatively small optic nerve head, (2) absent to small physiologic cup, (3) increased number of branches of the central retinal vessels within the disk, and (4) a normal, healthy-appearing nerve-fiber bundle layer with heaping up of at least the superior, nasal, and inferior fibers (Fig. 1). These disks are similar in many ways to those described by Rosenberg, Savino, and GlaserS,6 as being characteristic of pseudopapilledema. Presumably, a small physiologic cup is the

Correlation of the Optic Disc Size to Glaucoma Susceptibility

AbstractPrevious studies have suggested that a larger optic disc size in blacks as compared with whites is related to the increased glaucoma susceptibility in blacks. In an intraindividual bilateral comparison of 245 white patients with open-angle glaucoma, the authors evaluated whether the glaucomatous optic nerve damage was greater or less in the eye with the larger optic nerve head. Highly myopic eyes were excluded. The difference in optic disc area of one eye as compared with the contralateral eye was not significantly correlated to the differences in visibility of retinal nerve fiber bundles and mean visual field defect between the two eyes. Mean perimetric loss and the retinal nerve fiber layer index were not significantly higher in the eye with the larger or smaller optic nerve head. This indicates that in whites, high myopes excluded, the susceptibility to glaucomatous optic nerve fiber loss may be independent of the optic disc size.

Glaucomatous Optic Nerve Atrophy in Small Discs with Low Cup-to-disc Ratios

Glaucomatous optic nerve damage has generally been associated with high cup-to-disc ratios. Fifteen eyes of nine patients with increased intraocular pressure and glaucomatous visual field loss but low cup-to-disc ratios are reported. The optic disc area was significantly (P < 0.01) smaller than in 429 normal subjects and 556 glaucoma patients with high cup-to-disc ratios. Parapapillary chorioretinal atrophy was significantly larger and retinal nerve fiber bundles were significantly less visible than in the normal group. The latter two parameters were not significantly different in the glaucoma groups with low and high cup-to-disc ratios when the groups were matched for mean perimetric loss. The authors conclude that in eyes with small optic discs, glaucomatous optic nerve damage may be indicated more sensitively by parapapillary changes than by cup-to-disc ratios. Glaucomatous eyes with small optic nerve heads can have misleadingly low cup-to-disc ratios.

"Morning glory syndrome" and "Handmann's anomaly" in congenital macropapilla. Extreme variants of "confluent optic pits"?

Seventeen optic disks with morning glory syndrome were measured in absolute and relative size units (millimeters and parapapillary retinal vessel caliber) in 5 and 12 eyes, respectively. Their respective mean areas were 7.47 +/- 2.63 mm2 and 7.84 +/- 4.96 mm2. They were significantly (Mann-Whitney test) larger than 457 unselected normal optic nerve heads (2.69 +/- 0.70 mm2; p less than 0.0001) and 15 optic disks with pits (4.84 +/- 1.42 mm2; p less than 0.001). They are the largest optic nerve heads, probably with constant postnatal size, measured so far, and form part of a spectrum of optic disk anomalies and diseases whose frequency correlates with the size of the optic disk. This spectrum includes abnormally small optic nerve heads with increased prevalence of drusen, pseudopapilledema and nonarteritic anterior ischemic optic neuropathy, asymptomatic macrodisks with physiologic, "pseudoglaucomatous" macrocups, symptomatic macrodisks with pits and, finally, optic nerve heads with morning glory syndrome. The last-mentioned may be considered an extreme variation of optic disks with pits which have combined to form a single macropit covering the entire optic nerve head.