Adequate Vision Research Articles

Near Vision Impairment Predicts Cognitive Decline: Data from the Hispanic Established Populations for Epidemiologic Studies of the Elderly

To estimate the association between sensory impairment and cognitive decline in older Mexican Americans. A prospective cohort study. The Hispanic Established Populations for Epidemiologic Studies of the Elderly from five southwestern states. The sample consisted of 2,140 noninstitutionalized Mexican Americans aged 65 and older followed from 1993/1994 until 2000/2001. The outcome, cognitive function decline, was assessed using the Mini-Mental State Examination blind version (MMSE-blind) at baseline and at 2, 5, and 7 years of follow-up. Other variables were near vision, distance vision, hearing, demographics (age, sex, marital status, living arrangements, and education), depressive symptoms, hypertension, diabetes mellitus, stroke, heart attack, and functional status. A general linear mixed model was used to estimate cognitive decline at follow-up. In a fully adjusted model, MMSE-blind scores of subjects with near vision impairment decreased 0.62 points (standard error (SE)=0.29, P=.03) over 2 years and decreased (slope of decline) 0.13 points (SE=0.07, P=.045) more per year than scores of subjects with adequate near vision. Other independent predictors of cognitive decline were baseline MMSE-blind score, age, education, marital status, depressive symptoms, and number of activity of daily living limitations. Near vision impairment, but not distance vision or hearing impairments, was associated with cognitive decline in older Mexican Americans.

Trocar placement for laparoscopic abdominal procedures: a simple standardized method.

Minimal access approaches have been described for nearly all surgical procedures performed in the abdomen, with many manuals published and techniques described for a wide array of procedures accomplished laparoscopically. In contrast very few authors have investigated trocar placement in relation to optimal ergonomics and related technical considerations. Difficulties resulting from anatomical conditions, local pathology, adhesions, and patient habitus have been reported but rarely has any publication emphasized the role of poorly placed trocars. Correct trocar placement provides direct access to target organs, optimal vision of the operative field with a minimal loss of time and effort and a decrease in mental and muscular fatigue, and enhances recognition of structures and pathologic conditions. Less time is lost because of instruments competing for space (“working opposite” or “against” the camera, and “scissoring” or the “dueling swords” phenomenon). There is also less necessity for trocar relocation, not only cutting down operative time and costs, but considerably reducing complications and reducing the number of conversions from operative difficulties. Finally, correct placement of trocars should facilitate adequate and full vision of the operative field, making immediate recognition of mishaps possible as they occur and allowing immediate correction with a minimum of morbidity. This report is intended to provide the reader with recommendations for safe, adapted, worker-friendly laparoscopic access to the abdominal cavity through a standardized methodology of trocar placement, which is based on the location of the target organ, the procedure envisioned, and on patient and surgeon habitus. TECHNIQUE The anterior and lateral abdominal wall is here divided into four quadrants corresponding to the classical divisions, plus two triangles: thoracic, cephalad and pelvic, caudad (Fig. 1A). For each quadrant a schematic diagram depicts the placement of trocars along a semicircular line centered on the projection of the target organ, a line 16 to 18 cm long (the distance on the average surgeon’s hand, fingers spread apart, from the base of the palm to the tip of the medius [third finger]) (Fig. 1B). Landmarks on the anterior and lateral aspect of the abdomen assist the surgeon in determining the center of the semicircular arc in each of the six above-mentioned divisions. Advancing or retracting trocar placement along one of the axes or radii depends on the following: patient habitus (thickness of the abdominal wall); whether a 0-, 25-, 30-, or 45-degree scope is being used (the greater the angle of the optical end, the closer the scoping trocar should be inserted to the target organ); and surgeon preference. It is also obvious that the greater the thickness of the abdominal wall, the more the trocar should be inclined in the direction of the target organ to avoid excessive torque. The endoscope, which can be 3 mm, 5 mm, 7 mm, or 10 mm in diameter, can be moved from one trocar to another as needed and will always stay pointed at the target. Trocar size should be adapted to instrument and endoscope diameters as required. In the thoracic and pelvic triangles additional trocars can be placed in the subxyphoid and suprapubic areas. It must be remembered that in the thoracic triangle the abdominal esophagus and cardiac region are high, and because of the interposition of the left lobe of the liver the triangle is slightly deviated to the left. In combined operations such as the duodenal switch, nephroureterectomy, colectomy, and others, additional monitors may be needed. In left upper quadrant operations it must also be remembered that the ligament of Treitz projects at the intersection of two lines: one running from the xyphoid to the left anterosuperior iliac spine, and the other going from the umbilicus to the left shoulder. No competing interests declared.

Contact lens fitting over intrastromal corneal rings in a keratoconic patient

Intrastromal corneal ring segments have been used as a refractive surgery method for treatment of myopia. More recently, attempts have been made to use this surgical procedure in patients with keratoconus. A 51-year-old man with keratoconus came to the clinic for a contact lens refit. He had undergone surgical insertion of intrastromal corneal rings in his right eye 7 months earlier in an attempt to obtain acceptable vision without contact lenses. At the time of presentation, the patient was not satisfied with his vision in the right eye and requested an attempt to improve his vision with a contact lens. The resulting corneal shape after surgery presented some complications, but the patient was able to achieve 20/25-vision and adequate comfort in his right eye with a piggyback contact lens system. Insertion of intrastromal corneal rings may be beneficial in patients with early keratoconus or who are contact lens-intolerant. However, patients with more-advanced keratoconus are not likely to achieve adequate vision after the surgery and will require a contact lens. In addition, changes in the corneal anatomy created by the intrastromal rings may make contact lens fitting more challenging. The corneal irregularity may be exacerbated due to drastic variations in corneal elevation over the intrastromal ring and directly adjacent to the ring. This irregularity in elevation leads to difficulty in centering the lens on the eye and problems with bubbles forming under the contact lens over areas of corneal depression. When successfully fitted, contact lenses over intrastromal corneal rings can improve vision significantly.

Treatment of keratitis superficialis chronica of the dog with strontium 90

Corneal pannus is a disease which, if untreated, nearly always is progressive and may lead to blindness of the affected dog. A therapeutic standard is yet to be defined. Beta-ray irradiation with Sr-90 is often recommended on a casuistic basis, but systematic studies are sparse. The aim of the present study was to evaluate efficacy and to document side effects of radiotherapy with Sr-90. 17 animals were treated. 13 of them received treatment of 15 Gy surface dose twice within 2 days with additional medical therapy with ciclosporin and prednisolon. Only the more affected eye was treated with radiation which was applied with an eye-applicator, the other eye served as control. Four animals with already advanced impairment of vision received keratectomy, afterwards radiation was applied on both sides. Medical treatment alone led to deterioration in vascularization and spread of pigmentation in eleven of 13 (85%) of the control-eyes, density of pigmentation increased in eight of 13 (62%). After radiation therapy, almost all animals showed a marked initial improvement. Even if progressive disease occurred later on, further worsening as it happened in the control-eyes could be stopped in nine resp. ten of 13 eyes (69% and 77%). All animals with keratectomy and radiotherapy regained and preserved adequate vision. Besides short-term blepharospasm, no side effects were recorded. Corneal pannus is responsive to radiation therapy with Sr-90 and long-term benefit can be achieved. Side effects are minimal. Optimal sequencing of therapy and dosage still have to be examined.

Medical backgrounders: glaucoma.

Glaucoma is a leading cause of irreversible blindness in the world. Currently, glaucoma is diagnosed as a progressive optic neuropathy with characteristic optic disc and nerve fiber layer damage, usually associated with loss of visual function. The intraocular pressure (IOP) is the most important risk factor for the disease, although a significant proportion of patients do not have elevated IOP. Other risk factors include older age, African descent, myopia and family history of the disease. The ophthalmoscopic examination of the optic disc is essential to identify the signs of glaucomatous optic neuropathy, such as increased cupping, neuroretinal rim thinning or optic disc hemorrhages. Glaucomatous visual field loss usually starts in the periphery, and loss of central vision does not occur until late in the course of the disease. Visual function is most commonly assessed by standard automated perimetry; however, as many as 50% of nerve fibers can be lost before the appearance of visual field defects in this test. Newer technologies have been developed to find more sensitive ways to detect early glaucoma using both functional (short-wavelength automated perimetry and frequency-doubling perimetry) and structural (scanning laser topography, optical coherence tomography and scanning laser polarimetry) measurements. The management of glaucoma is based on lowering the intraocular pressure to prevent further optic nerve damage. Currently, there are five major classes of medications that are used to lower the intraocular pressure: Beta-adrenergic antagonists, adrenergic agonists, parasympathomimetics, prostaglandin-like analogues and carbonic anhydrase inhibitors. The goal of therapy is to maintain adequate vision for patients during their lifetime, keeping in mind the possible adverse effects of the drugs. If additional lowering of IOP is indicated or if medication fails to sufficiently lower the IOP, laser trabeculoplasty is usually the next step. If IOP is still not adequately controlled, incisional glaucoma surgery is indicated. Neuroprotective agents, which directly protect the optic nerve in glaucoma, are being evaluated in clinical trials.

Prevalence [correction of prevalance] of functional blindness, visual impairment, and related functional deficits among elderly Mexican Americans.

This report describes the prevalence and correlates of functional blindness and visual impairment among older Mexican Americans, using data on 2800 respondents from the Hispanic Established Populations for the Epidemiological Study of the Elderly. Bivariate and multivariate logistic regression analyses were used to examine the associations between corrected bilateral distant vision and sociodemographic characteristics, selected health conditions, self-reported health status, health care utilization, and functional dependence on the basis of assistance needed for basic and instrumental activities of daily living (ADLs). Using a modified Snellen test for distance visual acuity, 5% of older Mexican Americans were found to be functionally blind, and 13.5% were found to be visually impaired. Vision loss was significantly associated with older age, lower education, hypertension, diabetes, poor self-rated health, and hospitalization during the year prior to the interview. Over 50% of functionally blind subjects required assistance with at least one basic ADL, compared with 15% of those who were visually impaired and 8% of those who were not visually impaired. The prevalence of functional blindness in this sample of elderly Mexican Americans was higher than reported for the general elderly population, yet they also have higher rates of adequate vision because of the low prevalence of visual impairment. The results suggest a need for more research on the prevalence and impact of functional blindness and visual impairment on the health of older Mexican Americans.

Cataract intervention surgery: A community approach

We present a report of an on-going British Council Prevention of Blindness – sponsored Cataract Surgical Outreach in Inyi – a rural community in Oji River Local Government Area of Enugu State, Nigeria. The important of Community Women\'s group in the mobilization of patients and the community is documented. The eye care providers from the University of Nigeria Teaching Hospital, Enugu, which carried out the study, consisted of consultant Ophthalmologist, ophthalmic resident doctors, nurses and auxiliary staff. Of the 35 patients recruited over a two-month period, 17 males and 18 females, with age range from 51-80 years, mean age 57.8 years. Most patients (88.6%) had age-related cataract. All 35 patients had intra-capsular cataract extraction using a cryoprobe, under local anaesthesia. Three patients (8.6%) had post-operative complications, which are, residual soft lens matter, uveal prolapsed and up-drawn pupil. There was no case of post-operative infection. Rehabilitation was done with spectacles. The benefits of successful cataract operation and restoration of adequate vision as an effective motivator in overcoming patient\'s reluctance and socio-cultural barriers for surgery is highlighted. Nigerian Journal of Ophthalmology Vol. 8, No.1 (August 2000): pp 17-20 KEY WORDS : Primary eye care, cataract backlog, cataract surgical outreach, community women\'s group and motivators.

The causes and profile of visual loss in an onchocerciasis-endemic forest-savanna zone in Nigeria

In an onchocerciasis-endemic forest-savanna mosaic zone of southeastern Nigeria, blindness was found in 5.4% of 1,217 people who voluntarily attended for examination from a population of 14,000. Apart from cataract, the most important causes of blindness in the area were eye diseases that are known to be associated with onchocerciasis. Refractive error, although a non-onchocerciasis-related eye defect, was the number one cause of visual loss found in the study. The causes of blindness in our examined population are similar to what is found in onchocerciasis-endemic areas of the savanna zone and dissimilar from those found in the forest zone. In this forest-savanna mosaic zone, the prevalence of onchocerciasis was higher in the respondents with poor vision than in those with adequate vision. Similarly, low vision was found to be more common in people with high microfilarial loads, but people with high loads also tended to be older than those with moderate or low microfilarial loads, which might suggest that low vision was only a function of age. Nonetheless, analysis of our data shows evidence of an association between low vision and microfilarial load in adults aged 60 years and above. It is concluded that onchocerciasis in the forest-savanna mosaic zone of Nigeria has the features until recently associated only with savanna onchocerciasis, and that this should be taken into consideration in planning and executing onchocerciasis control programs in the area.

Reconstruction of total maxillectomy defects with preservation of the orbital contents.

Reconstruction after total maxillectomy with preservation of the orbital contents is technically more challenging than when the maxillectomy is combined with orbital exenteration. Reconstruction of such defects should (1) provide support to the orbital contents, (2) obliterate any communication between the orbit and nasopharynx, (3) reconstruct the palatal surface, and (4) achieve facial symmetry and a good aesthetic result. We report our experience in performing reconstructive surgery on 14 patients who had a total maxillectomy and preservation of the orbital contents using nonvascularized bone grafts for reconstruction of the orbital floor and maxilla, in conjunction with a soft-tissue free flap or pedicled muscle flap. The orbital floor was reconstructed using split ribs in six cases (42.9 percent), split calvaria in six cases (42.9 percent), and iliac crest graft in two cases (14.3 percent). A myocutaneous rectus abdominis free flap was used for soft-tissue reconstruction and resurfacing of the palatal mucosa in twelve patients (85.7 percent), and a temporalis muscle transposition was used in two elderly patients (14.3 percent). One patient died 2 days after surgery. Mean follow-up and aesthetic and functional results were assessed in the remaining 13 patients a minimum of 6 months postoperatively. In 9 of these 13 patients (69.2 percent), postoperative radiotherapy was administered. No reexplorations or free flap failures were observed. One rectus flap developed partial necrosis of the skin island intraorally without affecting the final result. All patients had adequate functional vision. One patient had a mild vertical dystopia; there were no cases of enophthalmos. Ectropion was the most common undesirable result and was present in 10 of 13 cases (76.9 percent). It was graded as mild in four cases (40.0 percent), moderate in four cases (40.0 percent), and severe in the remaining two cases (20.0 percent). Speech was considered normal in six cases (46.2 percent), near normal in six cases (46.2 percent), and intelligible in one case (7.7 percent). Chewing function was considered good (soft to unrestricted diet) in all cases except for one patient who was only able to eat a pureed diet. Aesthetic results after immediate reconstruction were considered good in nine cases (69.2 percent) and fair in four cases (30.8 percent). Primary reconstruction of total maxillectomy defects with orbital content preservation remains a complex problem without a perfect solution. The combination of nonvascularized bone grafts for orbital/maxillary reconstruction with a soft-tissue free flap is a safe, reliable, and effective method of maximizing postoperative functional and aesthetic results.

Transcylindrical cholecystectomy: new technique for minimally invasive cholecystectomy.

Minilaparotomy cholecystectomy presents exposition difficulties, and laparoscopy requires expensive equipment and additional training. Laparotomy is more painful, causes trauma to the abdominal wall, and requires a longer convalescence; it is also less aesthetic. We present a new technique for minilaparotomy cholecystectomy, transcylindrical cholecystectomy (TC), based on the introduction of a 3.8- or 5.0-cm diameter cylinder (10.0 cm long). The cylinder serves the purpose of separating and isolating the hepatocystic triangle from the surrounding structures, thereby providing a stable surgical field and adequate vision of the hepatocystic triangle so the technique can be performed safely. Patients who have been diagnosed with symptomatic cholelithiasis, who are convalescent from biliary pancreatitis, or who have acute cholecystitis have been treated consecutively by TC. We have carried out the procedure on 116 occasions, 94 using the 3.8-cm cylinder and 28 with the 5.0-cm cylinder; both cylinders were used in 6 cases. The indications for using the 5.0-cm cylinder were mainly cholecystitis, pancreatitis, choledocholithiasis, and difficulty with the 3.8-cm cylinder. The result is a 4.5- or 7.0-cm incision. We had difficulty recognizing the anatomy in 11 dissections so we had to enlarge the incision. We have not had accidents related to placement of the cylinder, hemorrhage, or bile duct injuries. The median operating time was 43 minutes, and the mean postoperative stay was 1.8 days. Postoperative FVC and FEV, reductions were 21.7% and 27.4%, respectively. The technique has proved fast, safe, and practicable using conventional material. The cost of TC is $701 (US).

Results of Excimer Laser Retreatment of Residual Myopia after Previous Photorefractive Keratectomy

Nine percent to 30% of all patients who undergo a single excimer laser photorefractive keratectomy (PRK) do not achieve an unaided visual acuity of 20/ 40 or better and may require optical correction to obtain adequate vision. The authors performed a retrospective analysis of the records of 164 patients who had undergone retreatment with the excimer laser for residual myopia after a previous PRK. Mean follow-up was 35.5 +/- 15.2 weeks (range, 26-104 weeks). The mean spherical equivalent (MSE) before retreatment was -2.59 +/- 1.36 diopter (D) (range, -0.50 to -7.75 D). The final MSE after reablation was -0.52 +/- 1.36 D (range, 2.50 to -5.50). Of the 164 patients, 107 (65.2%) obtained a final refraction within 1.00 D of emmetropia and 111 (67.3%) achieved an unaided visual acuity of 20/40 or better. Only 10 patients (6.1%) lost more than one Snellen line of best-corrected visual acuity. The final MSE result for the subgroup of patients who had a pre-retreatment myopia of between -0.50 and -1.90 D (-0.31 +/- 1.09 D) was significantly closer to emmetropia than that of the subgroup with a residual myopia of -4.00 to -7.75 D (-1.62 +/- 1.94 D). Excimer laser retreatment may provide a relatively safe and predictable method of correcting residual myopia after an earlier PRK with a 25% extra correction recommended for residual myopia.

Outcome of cataract surgery in central India: a longitudinal follow-up study.

An epidemiological follow-up study of patients who had intracapsular cataract extraction in a voluntary hospital and its associated eye camps in Central India has for the first time evaluated the outcome one year after surgery in terms of visual acuity, use of spectacles, and improvement in income and mobility. The findings indicate that under these fairly typical conditions, 92% of the cases have adequate vision of 6/18 or better one year after surgery. Information on high usage of spectacles and on considerable improvements in income and mobility after cataract surgery is also reported. The outcome for patients operated upon in eye camps was almost as favourable as for those operated upon in hospital. Although the small differences are not statistically significant, the comparative findings require cautious interpretation and give rise to the epidemiological issues which are briefly discussed in this paper.

SoftPerm contact lens fitting for a case of pellucid marginal degeneration

Pellucid marginal corneal degeneration (PMD) is a rare ectatic disorder which typically affects the inferior peripheral cornea in a crescentic fashion. The condition is most commonly found in males and usually appears between the 2nd and 5th decades of life affecting all ethnicities. The prevalence and aetiology of this disorder remain unknown. Ocular signs and symptoms of patients with PMD differ depending on the severity of the condition. Unless corneal topography is evaluated, early forms of PMD may often be undetected however, in the later stages PMD can often be misdiagnosed as keratoconus. Visual signs and symptoms include longstanding reduced visual acuity or increasing against-the-rule irregular astigmatism leading to a slow reduction in visual acuity. In rare cases, patients may present with a sudden loss of vision and excruciating ocular pain due to corneal hydrops or spontaneous perforation. The vast majority of PMD patients are managed using spectacles and contact lenses. Several surgical procedures have been used in an attempt to improve visual acuity when spectacles and contact lenses do not provide adequate vision correction. Since patients with PMD make poor candidates for laser vision correction, an awareness of the topographical and slit-lamp features of PMD will be useful to clinicians screening for signs of corneal abnormality before corneal refractive surgery. This review describes the clinical features of PMD, its differential diagnosis and various management strategies presently available.

Video Games

In the past few years, the video game explosion has permeated our everyday culture, involving in particular the younger generation. Video games once found only in arcades are now being manufactured for home use. This study seeks to analyze the value of video games as an activity program for geriatric populations in skilled nursing home facilities. Areas examined include resident acceptance and reaction to the program, how many residents utilized the equipment as well as how often, and those residents most interested and capable of participating in this activity. Suggestions for equipment adaptations are made to correct problems of poor visual clarity and awkward manipulation of controls. Video games may be successful small group recreational activities for those residents with adequate eye-hand coordination, vision and mental functioning.

Ultrasonic lithotripsy and soft tissue

It has been suggested that ultrasonic lithotripsy causes soft tissue damage by cavitation processes, by DNA alterations at subcavitational ultrasound levels, by thermic and mechanical trauma from the probe and from metal fragments splintered off the sonotrode. These issues were investigated in vitro and in vivo in the leporine bladder. Ultrasound intensity levels measured at the tips of sonotrodes never exceeded the cavitation threshold, so that cavitation processes are not involved in ultrasonic lithotripsy. The incidence of sister chromatid exchange in growing human lymphocytes was not altered, so that mutagenic effects appear unlikely. Thermic damage by the sonotrode is reliably prevented by irrigation cooling with 20 ml/min saline (20°C); higher flow rates are necessary for adequate vision in clinical practice. In spite of vibration amplitudes of up to 50 μ, the sonotrode causes only mucosal abrasion and submucosal hemorrhage; lesions of deeper layers of the bladder wall were never observed. Metal fragments are splintered off the sonotrode and nephroscope by contact, and this can largely be prevented by teflon coating of the wands. The fragments were washed out of leporine bladders within 24 h when instilled into the bladder cavity, and within 7 days when rubbed into the mucosa. In conclusion, significant soft tissue damage by ultrasonic lithotripsy was not observed. This corresponds to clinical experience with technique in 518 kidneys.

Vision Care for the Preschool Child With Handicaps

Although vision plays a major role in early childhood learning, many preschool children with handicaps do not receive adequate vision care. This article provides information about the number and diversity of preschool children with handicaps requiring vision services, and describes a vision care system designed to insure that these preschool children receive optimal vision care.

Visual disability and blindness secondary to refractive errors in Africa

Optical defects of the light-focusing apparatus of the eye are called errors of refraction. They are responsible for 13% of all significant vision loss in Kenya, ranking third of all causes, after cataract and trachoma. As the overall prevalence of such visual impairment in the Country is 3.7%, roughly 0.5% of the population can be said to need spectacles to obtain normal vision. The comparable figure for secondary school children in Nigeria has been found to be 2.4%. In addition, patients require special spectacles after cataract surgery to obtain adequate vision; without such spectacles these patients are still ‘blind’ by World Health Organization criteria. These glasses can be obtained through mission societies and various charitable organizations for as little as $5 per pair, and can be manufactured locally with available ophthalmic manpower and technology. Alternatives to spectacles such as contact lenses, intra-ocular lenses and Kerato-refractive surgery are not suitable for use in developing Countries.

Prismatic Scanning Method for Improving Visual Acuity in Patients with Low Vision

Frequently, patients with macular lesions and others who are visually handicapped do not receive adequate low vision care by ophthalmologists if a routine trial of low vision aids has no gratifying results. This paper describes for the first time a technique in which functional vision was achieved with the aid of prismatic scanning in patients for whom the usual low vision aids had proved ineffectual. The procedure in which prisms are used to achieve functional vision in patients with macular lesions is uncomplicated, inexpensive, and rapid; indeed, it can be used by an ophthalmologist in routine office practice with existing equipment.

Sequelae of severe xerophthalmia—a follow-up study

Two-hundred sixteen children with vitamin A deficiency were hospitalized in Hyderabad, India, between 1970 and 1977. Out of these, 22 died during hospitalization. Fifty-six children could be followed-up, of whom 32 had keratomalacia and 24 corneal xerosis. In the keratomalacia group, nine died of reasons attributable to severe protein-energy malnutrition within 3 to 4 months after discharge from the hospital, five became totally blind, nine monocularily blind, and nine had adequate vision, although four of these had leucomas. Of the blind children, no change in condition was noted in the 11 located 1 year after the initial 3 to 4 month follow-up period. Of the 24 children with corneal zerosis, two died within 3 months, 21 retained normal vision, and one had adequate vision with leucoma. The high death rate, i.e., 30% of the keratomalacia cases in this study helps to explain the low prevalence of keratomalacia observed in past and current community surveys. The high return to normalcy of vision in the corneal xerosis cases after proper treatment support the recommendation of treating all children with eye involvement before the keratomalacia state whenever possible, for greater assurance of subsequent eye improvement.

A simultaneous discrimination procedure for the measurement of vision in nonverbal children.

Few nonverbal developmentally disabled children ever receive adequate vision assessment because of their limited language skills. The present study details a simultaneous discrimination procedure for measuring subjective visual acuity in such children. A stimulus fading procedure was used to train a discrimination between Snellen Es differing in orientation, and a psychophysical tracking method was used to determine acuity thresholds. The procedure was tested with 11 nonverbal autistic and schizophrenic children and validated with four nonpsychotic children. Eight of the psychotic children were successfully examined in one to three sessions. Two of these children were identified as having significant acuity losses. The validity assessment showed that the experimental procedure resulted in thresholds equal to or slightly lower than those obtained with the Illiterate E chart.