Journal of the American Optometric Association最新文献

Background: There are relatively few studies on causes of childhood visual impairment. This study determines causes of visual impairment and resultant visual acuity among students enrolled at the Alabama School for the Blind (ASB).

Methods: All students enrolled at ASB during the 1996-1997 school year (N = 123) were examined between April 1994 and March 1997. A retrospective record review was performed to determine the primary cause of visual impairment and the visual acuity with best correction.

Results: The most frequent causes of visual impairment involved the optic nerve (30.9%): optic atrophy, 13%; Leber's optic atrophy, 4.1%; optic nerve hypoplasia, 5.7%; and glaucoma, 8.1%. Other common causes included congenital malformations other than those categorized separately (primarily aniridia), 12.2%; cataracts/aphakia, 13.8%; albinism, 13.0%; and retinitis pigmentosa, 8.1%. Nystagmus, chorioretinitis, and other conditions accounted for the remaining 22% of diagnoses. Best-corrected visual acuity in the better eye ranged from 20/20 to no light perception (NLP), with 44.3% having acuity better than 20/200; 26.2% having 20/200 to less than 400; 13.1% having measurable acuity of 20/400 or worse; 9% having light perception; and 7.4% having NLP.

Conclusions: Optic nerve disorders are the most common cause of visual impairment at ASB. Relatively few students (16.4%) had no measurable visual acuity.

Background: Preseptal cellulitis is a serious ocular condition that--if left untreated--has the potential to cross the septal barrier, spread to the posterior orbit, and may result in fatal complications. Because it is difficult to determine the pathogen responsible for any cellulitis without aspirating a culture sample, treatment is usually instituted by an assumption of the most common causative organisms, Staphylococcus or Streptococcus.

Case report: A 42-year-old black woman manifested signs and symptoms consistent with right preseptal cellulitis. Throughout treatment, visual acuity remained 20/20 for both eyes, extraocular muscles were unrestricted without pain, and anterior globe structures were clear. The patient was started on a regimen of 250-mg oral dicloxacillin four times a day. When no response was seen at 36 hours, the patient was changed to 500-mg oral ciprofloxacin every 12 hours. She responded to the 500-mg ciprofloxacin and recovered with no sequelae. An abscess, which had formed during the cellulitis, self expressed and this material was cultured. The cultures identified the responsible organism as Proteus species, an unexpected pathogen in a well-groomed patient.

Conclusion: This case demonstrates the need to consider alternate pathogens when treating preseptal cellulitis, change medications accordingly, and consider alternate treatments as needed.

Background: The authors wish to alert optometrists that an increased awareness of peripheral visual field is possible in selected patients with complete homonymous hemianopsia through the use of ground-in sectorial prisms.

Method: A case series of nine patients prospectively completed activities of daily living (ADL) questionnaires before and after the use of sectorial prism spectacles for the treatment of complete homonymous hemianopsias.

Results: Of the nine enrolled patients, seven reported subjective quantitative improvement in ADL scores on questionnaire responses and two patients did not report improvement.

Conclusion: Patients with homonymous hemianopic visual-field loss may improve their functional vision and activities of daily living through the use of hemianopic prism spectacles. These sectorial prisms--along with proper training--may enhance peripheral awareness through more efficient visual scanning skills.

The technology is here. Why aren't ODs jumping on board? Building a truly "paperless practice" isn't simply a matter of buying a few computers. Its cost can be measured in money, space, training time, and aggravation. And sometimes the doctors who need it most are the least able to implement it. This author discusses the pros and cons of the paperless practice and shows us how some "paperless" optometrists have done it in their offices.

Background: A bifocal rigid gas permeable (RGP) contact lens is now available that totally encapsulates an add segment of a different material within its inferior aspect. The purposes of this study were to determine the effects of the major lens and of its encapsulated segment region on the oxygen uptake rates of underlying cornea.

Methods: Corneal oxygen uptake rates of 10 human corneas were measured--both centrally and inferiorly--for non-wearing conditions and then immediately after 300-second wearing periods of a polymethylmethacrylate (PMMA) lens and of this RGP-encapsulated segment bifocal contact lens. Corneal responses associated with these three environmental conditions were compared statistically (i.e., without the influence of blink-driven tear flow).

Results: Under the nonblinking conditions maintained (i.e., with oxygen availability restricted to lens transmissibility alone), central corneal hypoxia was found for the RGP bifocal lens to be only 47% of that induced by the PMMA (Dk/L = 0) condition, while the cornea under the encapsulated segment of the bifocal lens averaged 78% of the hypoxic response induced by that same condition. Central site responses were found to be significantly different for the bifocal and the PMMA lens (p < 0.001), as they were for the two inferior sites with these two lenses (p < 0.001). All lens-related responses were found to be significantly different from the no lens condition (p < 0.001).

Conclusions: Using Smith's model (JAOA, 1997) to estimate lens transmissibility, the major lens of this RGP bifocal design appears to meet approximately 80% of the Holden-Mertz daily-wear oxygen requirement--even without post-lens tear exchange, but only about 25% of that requirement appears to be met beneath the encapsulated segment region. Efficient supplementary infusion of oxygen under this lens by blink-driven tear exchange, then, is necessary to maintain optimal corneal health.

As managed care inches closer to becoming the standard mechanism for delivering health benefits to American workers, we looked to see if the status of vision/eye health benefits have changed in the 1990s. Has vision care become a "mainstream" benefit?

Background: We present a case report on a rare presentation of a conjunctival malignant melanoma in a Native American woman. Malignant melanoma is a rare finding in the general population, and even more rare in Native Americans. Ultraviolet radiation (UVR) damage is postulated as a causal agent for its development and may explain why the vast majority of lesions are found in sun-exposed areas of the body. Human beings with lighter complexion are known to have a higher risk of malignant melanoma as well. Diagnosis and management issues are discussed.

Case report: A 44-year-old Native American woman manifested symptoms of general eye irritation for a period of 3 to 4 months. Examination revealed healthy eyes, except for the presence of an irregularly pigmented lesion on the tarsal conjunctiva of her left eye. Incisional biopsy further revealed this lesion to be malignant melanoma. Surgical excision of the entire lesion was performed. Six months status--post excision, the surgical wound site has healed completely and the patient has shown no signs of recurrent melanoma.

Conclusions: Our case is unique in that melanoma was found in a non-sun-exposed area of the body in a patient with a very dark complexion. Because of the high mortality rates and the association of malignant melanoma with cancer in other parts of the body, it is important for all eye care providers to recognize this lesion when present.

Background: Many patients with dyslexia report distortion to text when they are reading. After a successful pilot trial of an improvement in reading rate using ChromaGen haploscopic filters in comparison with the Intuitive Colorimeter, a full-scale, randomized, cross-over, double-masked, placebo-based trial was undertaken.

Method: The Wilkins rate of reading test was used to produce a baseline score, against which scores with ChromaGen lenses, placebo lenses, and a control were compared. Exclusion criteria included no formal dyslexia diagnosis, contraindications to contact lens wear, and uncorrected visual causes for reading difficulty.

Results: Forty-seven individuals successfully completed the trial, of which 41 reported distortion to the text (e.g., words appeared to move, were blurred, or patterns or spaces seemed to form in the text) when the patients were reading, and nine were color deficient. A comparison trial of ChromaGen lenses with placebo lenses demonstrated a significant improvement in the reading rate with ChromaGen lenses in individuals who reported distortion to text (p = 0.05) and a highly significant improvement in non-color-deficient individuals who reported distortion (p = 0.006). T-tests of the repeated measures showed that ChromaGen lenses produced a highly significant improvement in the rate of reading--over and above the placebo--in non-color-deficient individuals who reported distortion (p < 0.0001).

Conclusion: The significant increase in the reading rate amongst those who reported distortion suggests that by decreasing the distortion to text, a substantial proportion of dyslexic patients--in combination with their normal reading programs--would benefit from this aid.