Severe Optic Nerve Damage Research Articles

Effects of retinal ganglion cell loss on magno-, parvo-, koniocellular pathways in the lateral geniculate nucleus and visual cortex in glaucoma.

Glaucoma is a leading cause of world blindness, and retinal ganglion cell death is its pathological hallmark. There is accumulating evidence that glaucomatous damage extends from retinal ganglion cells to vision centers in the brain. In an experimental primate model of unilateral glaucoma, degenerative changes are observed in magnocellular, parvocellular, and koniocellular pathways in the lateral geniculate nucleus, and these changes are presented in relation to intraocular pressure and the severity of optic nerve damage. Neuropathological findings are also present in lateral geniculate nucleus layers driven by the unaffected fellow eye. Finally, there is information on changes in the visual cortex in relation to varying degrees of retinal ganglion cell loss. The implications of these findings for refining concepts regarding the pathobiology of progression, and the detection and treatment of glaucoma, are discussed.

Red and/or blonde hair association with pigmentary glaucoma in Israel

To assess the prevalence of red and/or blonde hair in a defined pigmentary glaucoma (PG) population and to compare their clinical findings with those of PG patients with black or brown hair. Hair color was studied in 35 consecutive PG patients and 35 consecutive primary open angle glaucoma (POAG) patients who served as controls. Patients were classified into red and/or blonde hair group or into black or brown hair group. Clinical characteristics were contrasted between PG patients of red and/or blonde hair with PG patients of black or brown hair. Of the 35 PG patients, 19 (54.3%) had red and/or blonde hair and 16 (45.7%) had black or brown hair. Of the 35 POAG patients, two (5.8%) had red and/or blonde hair and 33 (94.2%) had black or brown hair. This difference in prevalence of hair color is highly significant (P < 0.001; chi2). Clinical characteristics of the PG patients (age at initial diagnosis, gender, positive family history for glaucoma, initial IOP, refraction, severity of optic nerve damage and prevalence of retinal detachment) were similar in the red and/or blonde hair and the black or brown hair groups. A very high prevalence of red and/or blonde hair was found among PG patients in Israel. Should supportive evidence for this association accumulate subsequent to this report, screening of people with these hair colors for PG may be justified.

Severity of optic nerve damage in eyes with POAG is correlated with changes in the trabecular meshwork.

We wished to determine whether eyes with primary open-angle glaucoma (POAG) and differing severity of optic nerve damage also have differences in severity of trabecular meshwork changes.The trabecular meshwork and optic nerve from 26 eyes (14 donors) with the clinical diagnosis of POAG were studied. Severity of disease ranged from increased intraocular pressure (IOP) without damage to eyes with severe visual field loss. Optic nerve cross-sections were examined with light microscopy, and axonal counts were determined. We studied the trabecular meshwork around the circumference of each eye, examining sections from each quadrant with light and transmission electron microscopy. Morphometric measurements were made of the components of the cribriform region and statistically correlated with the axonal counts by the Pearson correlation coefficient.In eyes with advanced POAG, as determined by visual field loss, measurements of structures in the cribriform region of the trabecular meshwork and axon counts were in the same range as those reported previously in POAG. Axon counts showed a significant negative correlation with the amount of sheath-derived (SD) plaque material in the cribriform region: eyes with lower axon counts had larger amounts of SD plaques. Six eyes from four donors with increased pressure but no clinical signs of optic nerve damage showed no changes in axon counts and no increase in plaque material.Increasing severity of optic nerve damage in POAG is accompanied by an increase in the amount of SD plaque material in the trabecular meshwork.

Severity of Optic Nerve Damage in Eyes with POAG Is Correlated with Changes in the Trabecular Meshwork

Purpose: We wished to determine whether eyes with primary open-angle glaucoma (POAG) and differing severity of optic nerve damage also have differences in severity of trabecular meshwork changes. Methods: The trabecular meshwork and optic nerve from 26 eyes (14 donors) with the clinical diagnosis of POAG were studied. Severity of disease ranged from increased intraocular pressure (IOP) without damage to eyes with severe visual field loss. Optic nerve cross-sections were examined with light microscopy, and axonal counts were determined. We studied the trabecular meshwork around the circumference of each eye, examining sections from each quadrant with light and transmission electron microscopy. Morphometric measurements were made of the components of the cribriform region and statistically correlated with the axonal counts by the Pearson correlation coefficient. Results: In eyes with advanced POAG, as determined by visual field loss, measurements of structures in the cribriform region of the trabecular meshwork and axon counts were in the same range as those reported previously in POAG. Axon counts showed a significant negative correlation with the amount of sheath-derived (SD) plaque material in the cribriform region: eyes with lower axon counts had larger amounts of SD plaques. Six eyes from four donors with increased pressure but no clinical signs of optic nerve damage showed no changes in axon counts and no increase in plaque material. Conclusions: Increasing severity of optic nerve damage in POAG is accompanied by an increase in the amount of SD plaque material in the trabecular meshwork.

Peripapillary Vasoconstriction in the Glaucomas and the Anterior Ischemic Optic Neuropathies

Proximal constriction (retinal arteries narrower near the disk than further down the stream in the retina) was present in 96 of 226 eyes (42%) with classic glaucoma or normal-tension glaucoma, but it was present in only 11 of 206 eyes (5%) that were normal, had ocular hypertension, or had retinal disease not affecting the optic nerve. In cases of glaucoma with proximal constriction over only part of the disk circumference, its location corresponded to the sector with the greatest cupping in 60 of 66 cases (91%) and likewise corresponded to the sector in which the peripapillary zone of absent retinal pigment epithelium was widest in 48 of 55 cases (87%). Proximal constriction was also present in 16 of 45 eyes (36%) with nonischemic types of non-glaucomatous optic atrophy. The nonarteritic form of anterior ischemic optic neuropathy had proximal constriction in 19 of 28 eyes (68%), which was more frequent than in those with glaucoma (P = .017). Only one of nine eyes with the arteritic form of anterior ischemic optic neuropathy had proximal constriction, which was lower prevalence than in those with glaucoma (P = .066). General arterial narrowing (throughout the retinal course) was present in 111 of 204 (54%) of those with moderate optic nerve damage and 100 of 128 (78%) of those with severe optic nerve damage in all categories, compared with 29 of 208 (14%) of the controls with no optic nerve damage. Unlike proximal constriction, the generalized narrowing was related to severity of optic nerve damage and not to the disease category.

Clinically Detectable Nerve Fiber Atrophy Precedes the Onset of Glaucomatous Field Loss

Standardized perimetry and nerve fiber layer and color fundus photography were performed annually on 1344 eyes with elevated intraocular pressures. In 83 eyes, glaucomatous field defects developed that met rigid criteria on manual kinetic and suprathreshold static perimetry. Individual nerve fiber layer photographs were read by two masked observers. The more sensitive of the two identified nerve fiber layer defects in 88% of readable photographs at the time field loss first occurred; 60% (6/10) of eyes already had nerve fiber layer defects 6 years before field loss. In contrast, the nerve fiber layer was considered abnormal in only 11% (3/27) of normal eyes and 26% (84/327) of hypertensive eyes. The location of nerve fiber layer and field defects closely corresponded, but nerve fiber layer loss was generally more widespread. Examiner experience and severity of optic nerve damage influenced results. Mild focal defects were more readily recognized than more severe diffuse atrophy. Nerve fiber layer defects expanded with time, often by the development and coalescence of adjacent areas of damage.

Simultaneous recording of visual evoked potentials and electroretinograms in patients with unilateral opaque media

We studied the correlation between preoperative visual evoked potentials (VEPs) and postoperative visual acuities in patients with unilateral opaque media. The fellow eye was used as the control. The filtering effect due to opaque media could be assessed on the basis of the difference of the electroretinogram (ERG) threshold in the two eyes. 'Modified VEPs' were then calculated by eliminating the assessed filtering effects, which improved our ability to detect the potential for visual recovery. In the normal eye, the stimulus threshold for VEP is lower than that for ERG by 2 or 3 log units. Therefore should a higher stimulus threshold be found for VEP than ERG, severe optic nerve damage is highly probable in eyes with media opacties.

Intracapsular cataract extraction using cyclodialysis. A useful method

Thirty patients requiring cataract extraction for improved vision, and having concurrent primary open-angle glaucoma controlled with varying success by medication, had combined intracapsular cataract extraction and cyclodialysis performed by one surgeon. The average duration of follow-up was 22 months. Visual acuity deteriorated in one case in whom vision was limited to finger counting preoperatively. This patient had very advanced glaucoma and severe optic nerve damage; loss of vision was due to progression of visual field loss involving fixation. Visual acuity was unchanged in three cases; 2 had fingercounting vision, while one patient could discern hand movement preoperatively. All these patients also had far-advanced glaucomatous field loss and one, in addition, had senile macular degeneration. In all other cases there was a significant improvement in visual acuity. The mean intraocular pressure preoperatively was 22.8 mm Hg; three days post-operatively it was 13.6 mm Hg, after three months 17.6 mm Hg, after one year 17.8 mm Hg, and at the final follow-up visit 14.4 mm Hg. The number of medications required to control intraocular pressure decreased markedly. Combined cataract extraction with cyclodialysis appears to be a satisfactory procedure where there is an indication for combined cataract extraction with a glaucoma procedure. It should not be used in candidates who have had previous inflammatory glaucoma or who are not expected to tolerate long-term usage of echothiophate eyedrops following surgery.

Optic atrophy after seemingly trivial trauma.

This case is presented to emphasize the occurrence of severe optic nerve damage after seemingly minor trauma. It is noteworthy for the benign appearance of the globe and adnexa.