Spatial perception in normal and strabismic subjects: role of stereopsis and monocular clues.

PURPOSE: To evaluate the roles of binocular vision, monocular clues, and experience in spatial perception in a prospective, nonrandomized, case-control study. METHODS: A test was created consisting of three wood blocks arranged along the frontal plane inside Panum area. To produce some degrees of horizontal disparity, blocks were moved along a sagittal plane. Thirteen normal subjects (control group) and 13 nonamblyopic strabismic subjects (study group) were asked to identify, both under binocular and monocular vision, the position of the blocks in a series of 12 randomized presentations (phase 1). In phase II of the trial, a letter E in three different sizes, acting as a monocular clue, marked the three blocks. In both phases, the number of correct answers to the test during binocular and monocular vision was recorded. RESULTS: Binocular normal responses appeared greater than monocular normal responses and strabismic binocular responses in both phases (p < 0.001). Binocular strabismic responses and monocular answers of both groups appeared similar. CONCLUSIONS: In our experimental model, spatial orientation of strabismic subjects in binocular vision is substantially identical to that of normal subjects in monocular vision. Monocular clues were used in the same manner in both groups of subjects, and experience seemed to play no role in spatial localization of visual objects.

Vitreous hemorrhage following phakic anterior chamber intraocular lens implantation in severe myopia.

PURPOSE: To describe two cases of vitreous hemorrhage following phakic anterior chamber lens (AC-IOL) implantation in high myopia. CASE REPORT: In case 1, hemorrhage developed one month after surgery, without retinal involvement, and visual acuity (VA) resulted 20/200 after pars-plana vitrectomy (PPV). In Case 2, vitreous hemorrhage was complicated by retinal detachment (RD). PPV and silicone oil injection were performed, with AC-IOL removal and cristalline lens extraction. After 2 years the retina was attached and VA was 20/80. DISCUSSION: Only few cases of RD, posterior uveitis and endophthalmitis are reported following phakic AC-IOL implant. Vitreous hemorrhage could represent an additional posterior segment complication. Intraoperative manoeuvres, hypotony-induced posterior vitreous detachment and/or peripheral retina traction could play a role in engendering this complication in highly myopic eyes.

Older age as risk factor for deviation from emmetropia in pseudophakia.

PURPOSE: To find risk factors for deviation from emmetropia after cataract surgery in clinical practice. METHODS: We evaluated the refractive outcome in 106 patients who had underone phacoemulsification and in-the-bag IOL placement 115 +/- 10 days after surgery. Postoperative optical correction and refractive error (diopters of spherical equivalent--ED) were related to age and sex, pre-operative axial length and keratometric diopter power, and operative incision technique. RESULTS: Emmetropia was achieved in 15% of cases; 65% of eyes needed a myopic correction, averaging = 0.46 +/- 0.91 ED. The refractive error was 0.74 +/- 0.61 ED (< or = 1 ED in 77% of cases, < or = 2 ED in 97%). Both optical correction and refractive error were correlated to older age at the time of surgery (p=0.002 and p=0.001, respectively). Astigmatism appeared greater in clear-cornea incision than in limbar incision cases (p=0.05). CONCLUSIONS: The higher refractive error in patients aged over 73 years suggests that age may be a risk factor for deviation from emmetropia after cataract surgery.

Vitreous fluorophotometry and changes in blood-retinal barrier permeability induced by bendazac lysine.

Vitreous fluorophotometry was used to investigate the effect of Bendazac lysine on the blood retinal barrier in 12 insulin-dependent diabetics with mild background retinopathy. The study was a randomized, double blind, cross-over trial, drug versus Placebo. Each treatment period was of 4 months. The vitreous penetration coefficient was reduced by 21% (95% c.i. 12, 30; p = 0.001) by treatment with respect to Placebo.

Second Generation Binocular Polaroid Test.

BACKGROUND: The aim of the study was to introduce a new test to detect small areas of suppression in the binocular visual field and to lower the minimum age at which a suppression test could be identified correctly. Two tests were compared: the Binocular Polaroid Test (poltest), introduced in clinical practice a few years ago and used in screening programs for vision impairment; and the Second Generation Binocular Polaroid Test (polstar), more recently designed to have simpler answers than the poltest. METHODS: One hundred and eighty-two children were examined consecutively. To assess the validity of the two tests, sensitivity, specificity, predictive value, and phi coefficient were calculated. The applicability of the two tests and the speed of the responses was assessed by means of the test of probability of binomial distribution. RESULTS: The polstar has appeared to be simpler and easier in younger patients (age range 20 to 36 months, P = 0.078), and has shown 100% of specificity with a sensitivity of 84% for the polstar 1 and of 100% for the polstar 2. CONCLUSION: The results appear to demonstrate that the poltest has been improved, and that the polstar may be considered an interesting investigation device for early detection of monocular visual impairment.

[Etiopathogenetic role of metabolic, circulatory, sex factors and type and duration of diabetes in diabetic retinopathy. Investigation with vitreofluorophotometry]. / Ruolo eziopatogenetico di fattori metabolici, emovascolari, sesso, tipo e durata del diabete nella retinopatia diabetica. Indagine compiuta con la vitreofluorofotometria.

We have studied metabolic, circulatory and vascular parameters in a group of 57 diabetics (37 affected by IDDM, 20 affected by NIDDM; 35 were males, 22 were females). Goals of present study were: 1) quantitative evaluation of the blood retinal barrier; 2) influence of the metabolic state, blood pressure, sex, type and duration of the diabetes on the ocular conditions; 3) relationship between ophthalmoscopic appearance of the retina and vitreous fluorophotometric recordings. We concluded that: a) ocular alterations depend by lipidic metabolism, blood pressure, sex, type and duration of the diabetes; b) vitreous fluorophotometry has proved a good device for early detection of retinal damages in the diabetic retinopathy.

Binocular Polaroid Test for vision screening of pre-school age children.

We report the results obtained with the Binocular Polaroid Test in a large population screening devised to detect vision disturbances in pre-school age children. The Binocular Polaroid Test is a new test for rapid detection of small unilateral scotoma in the binocular visual field. The test was performed on 1566 children age 3 to 6 years in a field examination. The reliability of the test was controlled in a study examination. A complete study examination was performed in 60 of the 96 subjects with a positive response to the test. One hundred subjects selected at random among those with a negative response were used as controls. The study examination disclosed vision disturbances in 41 of the 60 children with a positive response to the Binocular Polaroid Test. The remaining 19 results were normal. No vision disturbances were detected in the control group. The predictive value and the "phi" coefficient were calculated. The results indicate that the Binocular Polaroid Test appears very suitable for vision screening in pre-school age children for whom an early diagnosis is of paramount importance for treatment and prognosis of a vision alteration.

Vitreous fluorophotometry in juvenile diabetics after oral fluorescein.

Vitreous fluorophotometry was performed in young patients (8 to 19 years old) affected by insulin-dependent diabetes mellitus, with no signs of diabetic retinopathy. Oral fluorescein was administered, and measures were used to prevent hypoglycemia during the examination. The results showed a breakdown of the blood-retinal barrier in nine (43%) of the 21 patients. The oral fluorescein method allows a satisfactory evaluation of ocular fluorescence profiles, with minimal risk of systemic side effects.

Binocular Polaroid test.

A test is presented for the detection of small suppression scotomas in strabismic and in anisometropic patients. Three small light-spots (the central is polarized) are viewed through Polaroid filters placed in front of the eyes. This arrangement produces the perception of the central spot only from one eye, but normal fusion provides the perception of three light-spots. Complete suppression of the central light indicates the presence of a scotoma in the binocular visual field. An inhibition scotoma in the non-dominant eye was found in all cases of small angle esotropia and of anisometropic amblyopia.

Unilateral visual agnosia.

A case of unilateral visual agnosia for all types of stimuli limited to the left visual hemifield and associated with a right occipital temporal vascular lesion is reported. Questions raised by this case of hemiagnosia as compared to previous ones are discussed.

Binocular disparity in visual evoked responses. Clinical evidence in normal and stereoblind subjects.

The authors have utilized a binocular flat or stereoscopic pattern (grating) to record visual evoked responses (VER) in normal and strabismic subjects. The aim was to find an electrophysiological correlate with the degree of binocular interaction in these subjects. The perception of the grating as tridimensional or flat derived from the disparity obtained with Polaroid filters placed in front of the eyes. In normal subjects, the results demonstrated a significant increase of VER amplitude during tridimensional perception of the pattern. In strabismic subjects the electrophysiological response was not correlated with the binocular conditions.

Proximal and accommodative convergence and age.

The authors have estimated the phoria for distant and near fixation in two groups of subject (mean age 27. 5+/- 4.4 and 59.2 +/- 8.2 years). Different accommodative stimuli were induced by adding minus lenses for distant fixation and plus lenses for near fixation. Statistical analysis of the experimental data indicates that, for distant fixation, the value of phoria per unit of accommodative stimulus is significantly lower presbyopic than in nonpresbyopic subject. Also, during near fixation, the accommodative convergence (AC/A ratio) is more reliable in the presbyopic subjects when the accommodative stimulus is progressively reduced. This varying behavior indicates in presbyopic subjects that proximal convergence is of greater relative importance in the determination of the fusion-free position. In nonpresbyopic subjects, accommodative convergence is the more important component.

Galactosemic enzyme levels in presenile cataracts.

Galactose-1-phosphate uridyl transferase and galactokinase activities have been measured in the red blood cells of a group of patients with "idiopathic" presenile cataract and of a group of nondiabetic patients with senile cataract. The activity of both galactosemic enzymes was found to be within the normal range in all the patients with presenile cataract. In the group of patients with senile cataract, galactokinase activity was normal in all 24 subjects examined, and galactose-1-phosphate uridyl transferase activity was moderately reduced in 3 of 14.

Bilateral papilloedema in long term therapy with lithium carbonate.

A 31-year-old white woman developed bilateral papilloedema whilst on lithium carbonate therapy for five years because of manic depressive illness. Oedema of the optic disc disappeared after lithium administration had been discontinued. To our knowledge this is the second case of this kind which has been reported in literature.

Vertical retraction syndrome.

A 14-year-old white boy, the second of 5 brothers, showed a congenital deficit of ocular motility in his left eye, characterized by limited elevation, marked retraction of the globe and narrowing of the palpebral fissure during upward gaze. The ocular movements in the other directions of gaze were normal with normal binocular vision and stereopsis. The characteristics of the motility defect and the results of the forced duction test suggest the possibility of an anomaly of superior rectus scleral insertion rather than of an innervational defect or of a muscular fibrosis.