Phakic implantation of a black intraocular lens in a blind eye with leukocoria

A 54-year-old woman with leukocoria from a white cataract requested evaluation for the undesired cosmetic appearance of her blind right eye. The eye was hypotonous from chronic total retinal detachment, and the lens appeared loose and partially resorbed. A solid, black poly(methyl methacrylate) intraocular prosthesis was placed in the phakic posterior chamber and sutured into the ciliary sulcus, leaving the lens undisturbed. The patient achieved excellent cosmesis and a significant improvement in self-image.

Postoperative reversal of complete (monocular) blindness in skull base meningioma: case report

BACKGROUND

Meningiomas of the anterior cranial fossa frequently present with impaired visual function. Recognition of this entity in the differential diagnosis of painless, progressive, and asymmetric optic neuropathy is important since reversal of visual loss is possible given timely surgical excision of the tumour.

METHODS

A 76-year-old man presented with no perception of light in his right eye and a reduced visual acuity of 20/60 in his left eye with a markedly constricted visual field. His visual deterioration had progressed over the previous three months and was not associated with headache. Ophthalmoscopy showed normal optic discs. MRI scanning showed a large frontal basal meningioma, which was subsequently resected.

RESULTS

The patient noticed an immediate improvement in his vision in his right eye. Visual acuity in his right eye improved to 20/50 at six weeks postoperatively and to 20/25 at five months, with corresponding improvement of the visual field.

CONCLUSION

Complete monocular blindness due to tumour compressing or distorting the anterior visual pathways does not preclude recovery following timely decompressive surgery, especially when the appearance of the optic disc is normal.

Ipsilateral globe penetration and transient contralateral amaurosis following retrobulbar anesthesia

PURPOSE

To report a rare complication of retrobulbar anesthesia with ipsilateral globe penetration and transient contralateral amaurosis.

DESIGN

Interventional case report.

METHODS

A 63-year-old woman complained of vision loss in the right eye immediately following cataract surgery on the left eye.

RESULTS

Right eye vision decreased to no light perception with clear media and normal fundus. The vision recovered to baseline in 12 hours. Left eye vision was checked and demonstrated only light perception. Fundus examination disclosed preretinal and vitreous hemorrhage. During vitrectomy of the left eye, a penetrating wound below the optic disk with retinal detachment was found.

CONCLUSION

The ipsilateral globe penetration wound depicts the mechanism of contralateral amaurosis following retrobulbar anesthesia of the case.

Sight and comfort: complex procedures in end-stage Stevens-Johnson syndrome

BACKGROUND

We describe our complex surgical techniques in the management of a patient with end-stage ocular surface disease from Stevens-Johnson syndrome.

METHODS AND RESULTS

Her severe discomfort due to absolute ocular dryness in the right eye was successfully treated with submandibular gland autotransplantation. Impending loss of the left eye due to repeated perforation and infection was prevented with a penetrating corneal graft covered by a new modification of a Cutler-Beard-type full-thickness lower lid skin advancement-flap. Visual rehabilitation was achieved by means of osteo-odonto-keratoprosthesis.

CONCLUSION

The procedures described allow the preservation of eyes doomed for enucleation, relief from severe discomfort and rehabilitation from corneal blindness. Due to their complex nature they require the collaborative subspecialist surgical skills of opthalmologists and maxillofacial surgeons.

The value of preoperative tests in the selection of blind patients for a permanent microelectronic implant

PURPOSE

To determine the best candidates (ie, those requiring lowest current levels delivered to the retina to elicit visual perceptions) for long-term implantation of a microelectronic retinal implant through a series of preoperative visual, psychophysical, and electrophysiological tests.

METHODS

This study protocol was granted an investigational device exemption by the Food and Drug Administration and was approved by the institutional review board at the University of Southern California. After informed consent was obtained, all subjects underwent the following preoperative tests: dark-adapted bright flash and 30-Hz flicker electroretinograms, electrical evoked responses (EERs) using a Burian-Allen corneal electrode to stimulate the globe, and psychophysical tests to evaluate the light and electrically elicited visual perceptions. Intraocular stimulation (IOS) of the retina was performed by an array of electrodes positioned on the internal limiting lamina.

RESULTS

Lower vision correlated with less sensitive psychophysical responses (P<.0001). Lower vision and less sensitive psychophysical tests correlated with higher EER values for stimulus pulse widths of 2 ms (P<.0008) and 4 ms (P<.0002). Lower IOS currents correlated with more sensitive psychophysical responses (P<.02) and lower EER values at 4 ms (P<.04).

CONCLUSIONS

Preoperative testing, especially psychophysical and electrophysiological tests to assess light and electrically driven visual responses, can help in evaluating patients for suitability for receiving a permanent microelectronic retinal implant. Further study is warranted.

Delayed optic nerve decompression for indirect optic nerve injury

OBJECTIVE

To test the efficacy of delayed optic nerve decompression in traumatic optic nerve injury.

STUDY DESIGN

Critical analysis of Proforma-based, prospectively accrued data of all cases with injury to surgery interval of greater than 2 weeks.

METHODS

Thirty-five cases with a median injury to surgery interval of 56 days (range, 16-374 d). Surgical decompression was undertaken only in cases that continued to have poor vision after treatment with steroids in conventional doses (1 mg/kg prednisolone). Pre- and postoperative visual acuity measurements were converted to the logMAR scale of visual acuity and the percentage of visual improvement was calculated.

RESULTS

Surgery was universally unrewarding in all 9 cases with persistent and complete blindness of greater than 2 weeks and no response to steroid therapy. Of the cases with some residual vision, 20 of 26 cases improved (mean percentage improvement, 41.0 +/- 5.7%). Cases were categorized on the basis of the injury to surgery interval into groups of 2 weeks to 2 months, 2 months to 4 months, and greater than 4 months. No significant difference was demonstrated in the probability or quantum of improvement in these groups (P =.97).

CONCLUSIONS

Optic nerve decompression remains useful as a salvage procedure for conventional dose steroid failed cases of traumatic optic neuropathy. In cases that are not completely blind, vision can be improved even when surgery is undertaken a few months after the injury.

Ceramic photocell implants could restore sight

Researchers are perfecting the use of ceramic photocells for retinal implantation. The work is being done at the Space Vacuum Epitaxy Center in Houston, TX. The photocells are the results of experiments with oxide detectors conducted in space using the Wake Shield Facility. Artificial retinas are constructed of 100,000 microscopic ceramic detectors attached to a polymer film, which disintegrates after implantation. Initially, four arrays will be implanted, totalling 400,000 detectors per eye. If successful, two additional arrays would be implanted. Human trials are expected to begin in 2002.

Reasons for poor cataract surgery uptake - a qualitative study in rural South Africa

OBJECTIVES

To understand the reasons for poor cataract surgery uptake in people with blindness or severe visual impairment in rural South Africa.

METHODS

A qualitative analysis of detailed, domiciliary interviews with a community-based random sample of elderly Zulus who were blind or severely visually impaired as a result of operable cataract, who had previously been invited for surgery but had failed to attend.

RESULTS

Fear of surgery and a fatalistic attitude to the inevitability and irreversibility of blindness in old age were the main reasons for failure to attend for surgery. There was a lower level of disability and perceived need than had been assumed for people with such poor visual acuity. Non-surgical western style health care for systemic illness was common but few patients had sought any form of assistance for their poor vision. Issues of cost and accessibility were relatively unimportant.

CONCLUSION

Provision of affordable and accessible cataract surgery for the blind and severely visually impaired members of a community does not guarantee that it will be taken up. Other barriers to surgery may be revealed when practical issues such as cost and accessibility are addressed. Perceptions of visual disability among subjects with cataract may differ from simple objective clinical standards.

Will retinal implants restore vision?

A number of research groups are developing electrical implants that can be attached directly to the retina in an attempt to restore vision to patients suffering from retinal degeneration. However, despite promising results in animal experiments, there are still several major obstacles to overcome before retinal prostheses can be used clinically.

Vision loss among diabetics in a group model Health Maintenance Organization (HMO)

PURPOSE

To report the management of diabetic retinopathy in one group model health maintenance organization and assess the quality of care.

METHODS

Cross-sectional study. A chart review of 1200 randomly identified patients with diabetes mellitus, continuously enrolled for 3 years in Kaiser Permanente (KP) Southern California, the largest provider of managed care in Southern California, was performed. A total of 1047 patients were included in the analyses. Patient characteristics as well as information from the last eye examination were abstracted. Charts from patients with visual acuity less than 20/200 in their better eye (legal blindness) were selected for extensive chart review to determine the cause of visual loss and the antecedent process of care. T tests or the Wilcoxon rank sum test was used to compare continuous variables. The chi(2) test or the Fisher exact test was used to compare categorical variables. All analyses were performed on the Statistical Analyses System (SAS Institute, North Carolina).

RESULTS

Our study population of 1047 diabetic patients was 51.7% male, had a mean age of 60.4 years, a mean duration of diabetes of 9.6 years, and a mean hemoglobin A1c of 8.3%. During the study period, 77.5% of patients received a screening eye examination with examination by an ophthalmologist, an optometrist, or review of a retinal photograph. Of those with a visual acuity assessment (n = 687, 65.6% of 1047), 1.5% had visual acuity of 20/200 or worse (legally blind) in the better eye, while 8.2% had this level of visual acuity in the worse eye. Of eyes with new onset clinically significant macular edema and visual acuity < 20/40, 40% had documentation of focal laser performed within 1 month of diagnosis. Of eyes with vitreous hemorrhage and visual acuity < 20/40, 50% had documentation of vitrectomy. Among eyes that had vitrectomy, over 80% had this procedure within 1 year of diagnosis of vitreous hemorrhage.

CONCLUSIONS

The current report is the largest study of diabetic retinopathy outcomes among patients enrolled in a prepaid health plan. Further research is necessary to investigate the impact of managed care on health outcomes.

An overview of the development of artificial corneas with porous skirts and the use of PHEMA for such an application

An overview of the efforts to develop functional polymeric artificial corneas (keratoprostheses) by incorporating a porous skirt is presented. The development of such a device by the author's group using poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels, as a combination of their homogeneous and heterogeneous states, and the rationale of this choice are also discussed. The latest results of the clinical trials with the PHEMA keratoprosthesis in human patients indicate a lower risk of the complications traditionally associated with the implantation of artificial corneas.

Glaucoma in China: how big is the problem?

AIMS

To derive preliminary estimates for the number of adults in China suffering from glaucoma, and project the burden of visual morbidity attributable to primary and secondary glaucoma.

METHODS

Age and sex specific data from two population surveys were applied to US Census Bureau population estimates for urban and rural China. It was assumed that data from Singapore were representative of urban China, and those from Mongolia were representative of rural China.

RESULTS

It was estimated that 9.4 million people aged 40 years and older in China have glaucomatous optic neuropathy. Of this number, 5.2 million (55%) are blind in at least one eye and 1.7 million (18.1%) are blind in both eyes. Primary angle closure glaucoma (PACG) is responsible for the vast majority (91%) of bilateral glaucoma blindness in China. The number of people with the anatomical trait predisposing to PACG (an "occludable" drainage angle) is in the region of 28.2 million, and of these 9.1 million have significant angle closure, indicated by peripheral anterior synechiae or raised intraocular pressure.

CONCLUSIONS

This extrapolation of data from two east Asian countries gives an approximate number of people in China suffering from glaucoma. It is unlikely that this crude statistical model is entirely accurate. However, the authors believe the visual morbidity from glaucoma in China is considerable. PACG is probably the leading cause of glaucoma blindness in both eyes, and warrants detailed investigation of strategies for prevention.

High-resolution two-dimensional spatial mapping of cat striate cortex using a 100-microelectrode array

Much of our understanding of the visuotopic organization of striate cortex results from single-electrode penetrations and serial recording of receptive field properties. However, the quality of these maps is limited by imprecision in quantifying electrode position, combining data from multiple laminae, and eye drift during the measurement of the receptive field properties. We have addressed these concerns by using an array of 100 closely spaced microelectrodes to investigate the two-dimensional visuotopic organization of layer IV in cat striate cortex. This array allowed simultaneous measurement of the receptive field properties of multiple single units on a regularly spaced grid. We found the relationship between cortical and visual space to be locally non-conformal: the receptive field locations associated with a closely spaced line of electrodes appeared randomly scattered in visual space. To quantify the scatter, we fitted a linear transformation of electrode sites onto the associated receptive field locations. We found that the distribution of the difference between the predicted receptive field location and the measured location had standard deviations of 0.59 degrees and 0.45 degrees in the horizontal and the vertical axes, respectively. Although individual receptive field positions differed from the predicted locations in a non-conformal sense, the trend across multiple receptive fields followed the maps described elsewhere. We found, on average, that the 13 mm2 of cortex sampled by the array mapped onto a 5.8-degrees) region of visual space. From the scaling of this map and a combination of the statistics of the receptive field size (2.7+/-1.5 degrees) and scatter, we have explored the impact of electrode spacing on the completeness and redundancy in coverage of visual space sampled by an array. The simulation indicated an array with 1.2-mm spacing would completely sample the region of visual space addressed by the array. These results have implications for neuroprosthetic applications. Assuming phosphene organization resembles the visuotopic organization, remapping of visual space may be necessary to accommodate the scatter in phosphene locations.

Cataract blindness and barriers to uptake of cataract surgery in a rural community of northern Nigeria

AIMS

A population based cross sectional survey was conducted to determine the magnitude of cataract blindness and the barriers to uptake of cataract services in a rural community of northern Nigeria.

METHODS

1461 people out of 1924 registered eligible people were examined. The study population was chosen by two stage cluster random sampling. In the first sampling stage 15 villages were randomly chosen while in the final stage 170 people who were 40 years and over were selected in each village. Each selected person had visual acuity recorded for both eyes. Those with vision of less than 3/60 in the better eye were assessed for cataract. People with cataract were asked why they had not sought medical attention.

RESULTS

A blindness prevalence of 8.2% (95% CI 5.8%-10.5%) was found among the sampled population. Cataract was responsible for 44.2% of the blindness. Thus, a cataract blindness prevalence of 3.6% was found. The cataract surgical coverage (people) was 4.0% and the couching coverage (people) was 18%. The main barrier to seeking cataract surgery was cost of the service (61%).

CONCLUSION

Some regions of the world still have high burden of cataract blindness that needs attention. Such areas need an effective free cataract outreach programme.

[Necessary visual information for restoring reading with a retinal implant in a blind patients with massive retinal degeneration of photoreceptors]

DEFINITION OF THE PROBLEM

Our goal is to determine the minimum of information necessary for elementary reading, using a retinal implant. This concerns particularly the fragmentation (pixellisation) of the presented image and its position in the visual field. Fragmentation corresponds to the number of electrodes available, the position of the image in the visual field is equivalent to the site of the implant on the retina.

MATERIAL AND METHODS

10 degrees x 10 degrees windows, containing isolated words or letters, were presented to six healthy subjects on a computer screen. A coupling between the computer and an eye tracker stabilizes these images in an area of the visual field. This coupling constantly corrects the position of the image on the screen according to the direction of gaze.

RESULTS

1) A rapid decrease of the performance is observed at a certain threshold of pixellisation, dependent on the eccentricity of presentation of the images. 2) In central vision, about 400 pixels are sufficient to recognize 80% of the four-letters words. At 10 degrees of eccentricity, about 1225 pixels are needed. 3) An acceptable comprehension of a text (identification of four words out of five), is impossible at eccentricities higher than 10 degrees 4) About 50 pixels are sufficient for a satisfactory recognition of isolated letters, independently of their eccentricity.

CONCLUSION

These data validate the method of investigation and provide valuable indications regarding minimal visual requirements in prosthetic vision.

[A survey and treatment of blindness in Gejiu City of Yunnan Province]

OBJECTIVE

To calculate the percentage of blindness in the mass and evaluate the current conditions of treatment for cataract.

METHODS

In accordance with the national unified standards and procedures, a clue survey of the people aged under 40 years and a general survey of the people over 40 years in Gejiu city, Yunnan province were carried out. In the mean time, operations were performed for the patients with cataract.

RESULTS

Of the total 361 214 persons being surveyed, there were binocular blindness in 1 037 cases (0.29%) and monocular one in 983 cases (0.27%). Of the cases with binocular blindness, 593 cases (57.18%), and of the monocular blindness, 617 cases (62.77%) could be treated. The leading causes of 1037 cases with binocular blindness were cataract (51.98%), injuries of the eye (19.96%), corneal opacity (16.00%), glaucoma (10.03%), refractive error and other ocular diseases (2.03%). The average prevalence rate in the female cases was higher than that of male cases (chi(2) = 53.48, P < 0.01). Blindness was associated with older age There were variations in the prevalence rates in different aboriginals and in cases with different occupations. Cataract was the main disease to cause both the monocular and binocular blindness. Among the patients with cataract 539 cases (90.98%) of binocular blindness and 500 cases (81.03%) of monocular blindness were curable. The cataract operation was performed on 738 cases with cataract, including 396 cases with binocular blindness and 342 cases with monocular blindness. At postoperative 3 months, the rate of the best corrected visual acuity (eye sight > 0.05) was accounted for 97.73%, the rate of the eye sight > 0.3, 86.36% and the rate of wearing glasses (including implantation of intraocular lens), 85.60%.

CONCLUSION

The prevalence of blindness is associated with the aboriginal, occupation, age and the sex. The leading cause of blindness is cataract. So the surgical restoration of vision in cases with cataract is the main measure in the prevention of blindness.

Light-driven retinal ganglion cell responses in blind rd mice after neural retinal transplantation

PURPOSE

Light-elicited retinal ganglion cell (RGC) responses after fetal neural retinal transplantation have not been demonstrated in animal or human subjects blind from outer retinal degeneration, despite apparent morphologic success. This study was designed to test the hypothesis that the functional success of retinal transplantation may be enhanced by using a young host retina (13 days old).

METHODS

At postnatal day (P)13 C3H/HeJ (rd/rd) retinal degenerate mice received a subretinal transplant, in one eye only, of neural retinal tissue isolated from newborn normal C57/BL6J mice. Between 33 and 35 days after transplantation, local electroretinograms (ERGs) and ganglion cell responses were recorded directly from the retinal surface using a differential bipolar surface electrode. Measurements were performed both with and without light stimulation. Similar recordings were also performed in age-matched eyes subjected to sham transplantation, in control eyes that were not subjected to surgery, and in animals eyes that underwent transplantation at 8 weeks of age. After the recordings, the eyes were processed for light and transmission electron microscopy.

RESULTS

Three of 10 mice showed bursts of ganglion cell action potentials (ON response only) as well as recordable intraocular ERGs over the transplant in response to 1-second and 200-msec light stimuli. Light-driven ganglion cell responses could not be recorded in areas outside the transplant in all transplant-recipient eyes, age-matched control eyes, and sham-transplantation eyes. Light responses also could not be recorded in animal eyes that received transplants at an older age (8 weeks). Electron microscopic examination confirmed the presence of photoreceptor outer segments in the areas affected by transplantation.

CONCLUSIONS

This study demonstrates the presence of light-driven ganglion cell responses after subretinal transplantation in a retinal degenerate model. This finding may reflect functional integration of the transplant with the host, but a rescue effect on remaining host photoreceptors cannot be ruled out. The findings suggest, however, that modification of host parameters, such as host age, may be important approaches for improving the functional success of retinal transplantation.

Cyclodiode laser therapy for painful, blind glaucomatous eyes

AIMS

To determine the ability of cyclodiode laser treatment to relieve discomfort in painful blind glaucomatous eyes.

METHODS

30 eyes underwent cyclodiode to reduce intraocular pressure (IOP) and relieve pain. Patients graded their pre-cyclodiode and post-cyclodiode pain.

RESULTS

After a minimum follow up of 6 months, a single cyclodiode treatment lowered mean IOP from 51 mm Hg (95% CI plus or minus 3.7 mm Hg) to 26 mm Hg (95% CI plus or minus 5.8 mm Hg) providing pain relief in 73.3% (22/30). After retreatment of six eyes, mean IOP was reduced to 22 (95% CI plus or minus 5.3) mm Hg and pain relief was obtained in 96.7% (29/30). For eyes achieving pain relief after one treatment, IOP was reduced by >30% in 81.0% (17/21). For eyes not achieving pain relief after one treatment, IOP was reduced by >30% in only 22.2% (2/9) (p=0.0042, Fisher's exact test).

CONCLUSION

Cyclodiode was highly successful in providing pain relief in painful blind hypertensive glaucomatous eyes. The best predictor of successful pain relief was IOP reduction of > 30% from baseline.