Shadows of thought: shifting lateralization of human brain electrical patterns during brief visuomotor task.

Dynamic spatial patterns of correlation of electrical potentials recorded from the human brain were shown in diagrams generated by mathematical pattern recognition. The patterns for "move" and "no-move" variants of a brief visuospatial task were compared. In the interval spanning the P300 peak of the evoked potential, higher correlations of the right parietal electrode with occipital and central electrodes distinguished the no-move task from the move task. In the next interval, spanning the readiness potential in the move task, higher correlations of the left central electrode with occipital and frontal electrodes characterized the move task. These results conform to neuropsychological expectations of localized processing and their temporal sequence. The rapid change in the side and site of localized processes may account for conflicting reports of lateralization in studies which lacked adequate spatial and temporal resolution.

Human neuroelectric patterns predict performance accuracy.

In seven right-handed adults, the brain electrical patterns before accurate performance differed from the patterns before inaccurate performance. Activity overlying the left frontal cortex and the motor and parietal cortices contralateral to the performing hand preceded accurate left- or right-hand performance. Additional strong activity overlying midline motor and premotor cortices preceded left-hand performance. These measurements suggest that brief, spatially distributed neural activity patterns, or "preparatory sets," in distinct cognitive, somesthetic-motor, and integrative motor areas of the human brain may be essential precursors of accurate visuomotor performance.

Response preparation and inhibition: the role of the cortical sensorimotor beta rhythm.

Paradigms requiring either a GO or a NO-GO response are often used to study the neural mechanisms of response inhibition. Here this issue is examined from the perspective of event-related beta (14-30 Hz) oscillatory activity. Two macaque monkeys performed a task that began with a self-initiated lever depression and maintenance (sustained motor output) and required a visual pattern discrimination followed by either a lever release (GO) or continued lever-holding (NO-GO) response. Analyzing simultaneous local field potentials (LFPs) from primary somatosensory, frontal motor, and posterior parietal cortices, we report two results. First, beta oscillation desynchronized shortly after stimulus presentation, the onset of which was approximately the same for both the GO and NO-GO conditions ( approximately 110 ms). Since it is well known that beta desynchronization is a reliable indicator of movement preparation, this result suggests that early motor preparation took place in both conditions. Second, following the GO/NO-GO decision ( approximately 190 ms), beta activity rebounded significantly ( approximately 300 ms) only in the NO-GO condition. Coherence and Granger causality measures revealed that the dynamical organization of the rebounded beta network was similar to that existing during the sustained motor output prior to stimulus onset. This finding suggests that response inhibition led to the restoration of the sensorimotor network to its prestimulus state.

Titration kinetics of Asp-85 in bacteriorhodopsin: exclusion of the retinal pocket as the color-controlling cation binding site.

The spectrum (the purple blue transition) and function of the light-driven proton pump bacteriorhodopsin are determined by the state of protonation of the Asp-85 residue located in the vicinity of the retinal chromophore. The titration of Asp-85 is controlled by the binding/unbinding of one or two divalent metal cations (Ca2+ or Mg2+). The location of such metal binding site(s) is approached by studying the kinetics of the cation-induced titration of Asp-85 using metal ions and large molecular cations, such as quaternary ammonium ions, R4N+ (R = Et, Pr, a divalent 'bolaform ion' [Et3N+-(CH2)4-N+Et3] and the 1:3 molecular complex formed between Fe2+ and 1,10-phenanthroline (OP). The basic multi-component kinetic features of the titration, extending from 10(-2) to 10(4) s, are unaffected by the charge and size of the cation. This indicates that cation binding to bR triggers the blue --> purple titration in a fast step, which is not rate-determining. In view of the size of the cations involved, these observations indicate that the cation binding site is in an exposed location on, or close to, the membrane surface. This excludes previous models, which placed the color-controlling Ca2+ ion in the retinal binding pocket.

Sex comparison of neuronal Fos immunoreactivity in the rat vomeronasal projection circuit after chemosensory stimulation.

In rodents, reproductively relevant pheromonal cues are detected by receptors in the vomeronasal organ, which in turn transmit this information centrally via the accessory olfactory bulb, the medial nucleus of the amygdala, the posterior medial bed nucleus of the stria terminalis and the medial preoptic area. In the rat, more neurons are present in males than in females at virtually every relay in this vomeronasal projection circuit. Using Fos immunoreactivity as a marker of neuronal activation, we compared the ability of pheromonal cues derived from the urine and feces of estrous or anestrous female rats to activate neurons in this vomeronasal projection circuit in sexually experienced, gonadectomized male and female rats which were chronically treated in adulthood with a high dose of testosterone propionate (5 mg/kg). When compared with rats killed after 2 h of exposure to clean bedding, male and female subjects exposed for 2 h to bedding from estrous females had similar and significant increments in the number of Fos-immunoreactive neurons at each level of the vomeronasal projection circuit, including the granular layer of the accessory olfactory bulb, the posterior dorsal portion of the medial amygdaloid nucleus, the posterior medial portion of the bed nucleus of the stria terminalis and the medial preoptic area. Exposure to bedding from anestrous females stimulated similar and significant increments in Fos immunoreactivity in most of these same brain regions. Chemosensory stimulation failed to augment Fos immunoreactivity in neurons located in the ventrolateral subregion of the ventromedial nucleus of the hypothalamus or in the midbrain central tegmental field, sites at which mating has previously been shown to augment Fos immunoreactivity in both sexes. Finally, chemosensory stimulation augmented Fos immunoreactivity in the nucleus accumbens shell and core, two regions receiving dopaminergic afferents which have been implicated in sexual reward. On two occasions all subjects were given simultaneous access to bowls containing bedding from estrous versus anestrous females. Both males and females spent significantly more time investigating the estrous bedding, although the total time spent investigating either type of bedding was significantly greater in males. The results suggest that the previously established sexual dimorphism in the morphology of the rat's vomeronasal projection circuit is not reflected in the functional responsiveness of neurons in this circuit to chemosensory cues emitted by female conspecifics.

Clinical characteristics of choroidal neovascular membranes.

Eighty-three choroidal neovascular membranes (CNVMs) associated with pathologic entities other than age-related macular degeneration (study group) were compared with 64 CNVMs associated with macular degeneration (comparison group). Nine CNVMs (11%) in the study group, compared with 28 CNVMs (44%) in the comparison group, were occult membranes. Of the remaining well-defined CNVMs, 16 (22%) in the study group, compared with 21 (58%) in the comparison group, were subfoveal. Of the well-defined subfoveal membranes, four (25%) in the study group, compared with 17 (81%) in the control group, were large (greater than 1500 micron in size). All large subfoveal membranes occurred in patients over 55 years of age. Thus, in this study the majority of CNVMs associated with pathologic entities other than age-related macular degeneration were well defined and not subfoveal at initial presentation. The majority of CNVMs associated with macular degeneration were occult or subfoveal. Membranes in patients over 55 years of age, regardless of cause, were commonly found to be occult or subfoveal at presentation.

Choroidal neovascularization in black patients.

OBJECTIVE: To characterize choroidal neovascularization (CNV) in black patients examined at a retinal disease referral center. DESIGN: Retrospective review of the medical records of all patients diagnosed as having CNV to identify black patients with CNV. SETTING: Single tertiary retinal referral center that included four ophthalmologists. PATIENTS: All patients diagnosed as having CNV between April 1990 and October 1992. MAIN OUTCOME MEASURES: Prevalence, demographic information, fundus photographic and fluorescein angiographic characteristics, natural history, and response to laser photocoagulation of CNV in black patients. RESULTS: Black patients comprise 15% of all patients seen at this center. Of 1725 patients identified as having CNV who were seen at the center during a 2.5-year period, only 25 were black (1.4%). In these patients, CNV was associated with a variety of retinal diseases, the most frequent being age-related macular degeneration. The average age of the study group was 54 years, women outnumbered men 2:1, and 13 of the patients developed bilateral lesions. Twelve of the 38 lesions were extrafoveal on presentation, and five of these were peripapillary. In the laser-treated eyes, recurrence of CNV was frequent and associated with visual loss. CONCLUSIONS: Choroidal neovascularization seems to be rare in blacks among a retinal disease referral center population. The overall presentation, natural history, and response to laser treatment seems to be similar to that of white patients. No feature of CNV in black patients was identified that would suggest that results of randomized clinical trials of laser photocoagulation for CNV are not valid for these patients.

Detecting recurrent choroidal neovascularization. Comparison of clinical examination with and without fluorescein angiography.

OBJECTIVE/DESIGN: To evaluate prospectively the ability of three retina specialists to detect recurrent choroidal neovascularization (CNV) after clinical examination alone and then with fluorescein angiography at 3 and 6 weeks and at 3, 6, 9, and 12 months after laser photocoagulation. SETTING: Single tertiary retinal referral center. PATIENTS: All patients who had laser treatment for CNV within 14 months of their study visit. One hundred thirty-seven eyes of 134 patients were evaluated during 401 visits. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, and negative predictive value of clinical examination with biomicroscopy to detect recurrent CNV when defined as leakage on the periphery of the laser-treated area on the fluorescein angiogram. RESULTS: Ninety-seven definite or probable recurrences in 56 eyes were identified on the fluorescein angiogram. Clinical examination had a sensitivity of 59%, specificity of 94%, positive predictive value of 76%, and negative predictive value of 88%. These figures varied somewhat by underlying cause, age, time since treatment, and lesion location. Using either a reported or measured loss of vision with the results of biomicroscopy as an indication of recurrence increased the sensitivity to 77% but reduced the specificity to 81%. CONCLUSIONS: Clinical examination probably cannot replace fluorescein angiography in detecting all recurrent CNV after laser treatment. However, for follow-up visits in which recurrent CNV was not suspected on biomicroscopy, definite or questionable recurrent CNV was identified on the fluorescein angiogram only 12% of the time, while the absence of recurrent CNV using this method was confirmed 88% of the time.

Natural course of poorly defined choroidal neovascularization associated with macular degeneration.

We obtained follow-up data on 84 eyes with age-related macular degeneration and poorly defined angiographic leakage presumed to represent choroidal neovascularization. A poorly defined neovascular membrane was presumed to be present when subsensory retinal fluid was present in association with choroidal leakage on fluorescein angiography and in which the extent of leakage was not well defined. Among the 84 eyes, the average initial visual acuity was 20/80. In 75 (89%) of 84 eyes, the leakage involved the foveal center at initial presentation. At follow-up (average, 28 months; range, six to 53 months), the average visual acuity was 20/250; the final acuity declined at least three but less than six lines in 18 eyes (21%) and six or more lines in 35 eyes (42%). There was a statistically significant difference in the percentage of eyes that developed moderate or severe visual loss among eyes that progressed to disciform scarring compared with eyes that continued to manifest poorly defined leakage without evidence of scarring. Given that most severe visual loss associated with macular degeneration can be attributed to consequences of neovascular membranes and that many membranes associated with age-related macular degeneration are poorly defined, our study results support the possibility that poorly defined neovascular membranes represent a major cause of severe visual loss among the elderly in the United States.

The long-term effects of visible light on the eye.

The relationship between exposure to sunlight and senile cataract, age-related macular degeneration, pterygium, and climatic droplet keratopathy was examined in 838 watermen who work on the Chesapeake Bay. The presence and severity of lenticular, corneal, and macular changes were assessed by either clinical examination or from stereo macular photographs. From detailed exposure histories, ocular exposure was estimated for three bands of visible radiation-violet (400 to 450 nm), blue (400 to 500 nm), or all visible (400 to 700 nm)-as well as for UV-A (320 to 340 nm) and UV-B (290 to 320 nm). The results with each band of visible radiation were similar. Neither cortical nor nuclear cataract was associated with ocular exposure to blue or all visible radiation, but pterygium and climatic droplet keratopathy were more common with higher exposures. Compared with age-matched controls, patients with advanced age-related macular degeneration (geographic atrophy or disciform scarring) had significantly higher exposure to blue or visible light over the preceding 20 years (odds ratio, 1.36 [1.00 to 1.85]) but were not different in respect to exposure to UV-A or UV-B. These data suggest that high levels of exposure to blue or visible light may cause ocular damage, especially later in life, and may be related to the development of age-related macular degeneration.

Are antioxidants or supplements protective for age-related macular degeneration?

OBJECTIVES: The relationships between fasting plasma levels of retinol, ascorbic acid, alpha-tochopherol, and beta-carotene and age-related macular degeneration (AMD) were studied in a population enrolled in the Baltimore Longitudinal Study of Aging (BLSA), in which most of the data were collected 2 or more years before assessment of macular status. DESIGN: A total of 976 participants in the study were scheduled for a biennial examination from January 1988 through January 1, 1990, which included taking lens and macular photographs. A total of 827 (85%) of the participants had fundus photographs taken, and most plasma data were available for 82% of those subjects with fundus photographs. Age-related macular degeneration was defined as neovascular changes, geographic and nongeographic atrophy, large or confluent drusen, or hyperpigmentation. A total of 226 cases of AMD were available for analysis. RESULTS: Logistic regression analyses suggested that alpha-tocopherol was associated with a protective effect for AMD, adjusted for age, sex, and nuclear opacity. An antioxidant index, including ascorbic acid, alpha-tocopherol, and beta-carotene, was also protective for AMD. Our conclusions must be tempered with the knowledge that the population under study was basically well nourished, and few individuals had any clinically deficient status. The study cannot exclude the possibility that quite low levels of micronutrients, lower than those observed in this study, might be risk factors for AMD. CONCLUSIONS: The data suggest a protective effect for AMD of high plasma values of alpha-tocopherol. An antioxidant index, composed of plasma ascorbic acid, alpha-tocopherol, and beta-carotene, was also protective. The use of vitamin supplements to prevent AMD is not supported by these data, which showed no protective effect of vitamin use.

Loculated fluid. A previously undescribed fluorescein angiographic finding in choroidal neovascularization associated with macular degeneration. Macular Photocoagulation Study Reading Center.

The Foveal Photocoagulation Study, a component of the Macular Photocoagulation Study, is designed to evaluate whether laser treatment can reduce the risk of severe visual loss in eyes with well-defined choroidal neovascular membranes associated with macular degeneration that extend through the foveal center. On one third of the 554 baseline angiograms of study patients enrolled in and whose eyes were graded in the study as of January 31, 1990, the Reading Center staff has noted an unusual pattern of hyperfluorescence in the late-transit frames that has not been described previously. This pattern, which we call "loculated fluid," consists of a well-demarcated area of hyperfluorescence that appears to represent pooling of fluorescein in a compartmentalized space anterior to the choroidal neovascular leakage. Although the loculated fluid may conform to a pattern of typical cystoid macular edema, it can also pool within an area deep to the sensory retina in a shape that does not bear any resemblance to cystoid macular edema. This pattern is important to recognize because it (1) should not be confused with the angiographic pattern or extent of choroidal neovascularization and (2) should be differentiated from a serous detachment or tear of the retinal pigment epithelium.

Relationship of drusen and abnormalities of the retinal pigment epithelium to the prognosis of neovascular macular degeneration. The Macular Photocoagulation Study Group.

We graded macular features of 127 fellow eyes of participants in the Macular Photocoagulation Study who had an extrafoveal choroidal neovascular membrane secondary to age-related macular degeneration in the first eye and no initial evidence of the neovascular form of age-related macular degeneration in the fellow eye. Our aims were to determine the relationship of drusen characteristics and retinal pigment epithelial abnormalities to the risk of subsequent development of neovascularization in the fellow eye and the risk of subsequent development of recurrent neovascular membranes after photocoagulation in the first eye. Regression analysis demonstrated that the presence of large drusen and focal hyperpigmentation of the retinal pigment epithelium were independent risk factors for the subsequent development of neovascularization in the fellow eye (relative risk, 2.4 and 2.5, respectively). Only 10% of eyes with no large drusen or any retinal pigment epithelial hyperpigmentation compared with 58% of eyes with both large drusen and retinal pigment epithelial hyperpigmentation developed neovascularization in the fellow eye within 5 years. Using multivariate Cox regression analysis, we noted that the risk of developing recurrent neovascular membranes in the first eye was significantly increased when large drusen (relative risk, 2.8) were noted in the fellow eye at the time of laser treatment in the first eye. Fundus features in the fellow eye appear to help identify patients at high risk of developing visual loss from recurrent neovascular membranes following laser treatment in the first eye and from development of a neovascular membrane in the fellow eye.

The grading and prevalence of macular degeneration in Chesapeake Bay watermen.

A new grading scheme was developed to classify the fundus features of macular degeneration. This scheme identifies the earliest fundus changes associated with macular degeneration, as well as specific drusen characteristics felt to be associated with an increased risk of developing the exudative forms of this disease. Agreement between two graders using this scheme indicated good interobserver reliability. Using this scheme, fundus photographs of 777 participants were graded in a population-based study of watermen from the eastern shore of Maryland. The prevalence of at least one druse within 1500 microns of the foveal center was extremely common (over 80% in each age group over 30 years of age) and not age related. The prevalence of large, confluent, or soft drusen was relatively uncommon and was age related; by the eighth decade, 26% of all participants had large or soft drusen, and 17% of them had confluent drusen. These latter characteristics are more likely to be markers of early changes consistent with age-related macular degeneration rather than simply the presence of a few drusen.

Clinicopathologic correlation of occult choroidal neovascularization in age-related macular degeneration.

We report the clinicopathologic features of an eye with occult choroidal neovascularization associated with age-related macular degeneration. Ophthalmoscopic findings at presentation included subretinal fluid and lipid. We noted angiographic staining of irregularly elevated areas of retinal pigment epithelium. In the late phase of the angiogram, fluorescein leakage at the level of the outer retina was observed that did not correspond to well-demarcated areas of hyperfluorescence in earlier phases. The patient was randomized to treatment in a pilot trial comparing the effects of grid laser treatment with the effects of no treatment for occult choroidal neovascularization. Three weeks after treatment, some of the subretinal fluid had cleared and vision improved. The patient died 6 weeks after laser treatment. Histopathologic study disclosed a subretinal pigment epithelial fibrovascular membrane. Neovascularization originated from the choroid.

Availability of color fundus photographs from previous visit affects practice patterns for patients with diabetes mellitus.

OBJECTIVE: To determine whether access to color fundus photographs from a patient's previous visit would alter the recommendations rendered to a cohort with diabetic retinopathy. PATIENTS AND METHODS: One hundred sixty patients with diabetic retinopathy returning for a follow-up visit and who had color fundus photographs obtained at a previous visit were evaluated by trained retina specialists. Their clinical impression and recommendations regarding management of diabetic retinopathy were recorded without reference to previous photographs. Color fundus photographs from the patient's most recent visit were then reviewed and new recommendations with regard to appropriate treatment and follow-up were recorded. RESULTS: In 21% of cases, after reviewing the patient's most recent color fundus photographs, the clinical recommendation changed. In 14% of cases, photographs clearly demonstrated that the patient's condition was stable or improved, resulting in a change from recommending treatment to recommending deferral of treatment. In 4% of cases, photographs clearly demonstrated clinical worsening and the recommendation was changed from observation to treatment. In 3% of cases, review of photographs prompted a change in the recommended follow-up interval. CONCLUSION: Access to color fundus photographs from a patient's previous visit frequently changed the clinical recommendations made to patients with diabetic retinopathy regarding appropriate treatment and follow-up. Availability of color fundus photographs therefore has implications about quality of care and may affect the cost of care.

Causes of blindness and visual impairment in a population of older Americans: The Salisbury Eye Evaluation Study.

OBJECTIVE: To determine the causes of blindness and visual impairment in a population-based sample of older Americans. METHODS: A random sample of 3821 residents of Salisbury, Md, between the ages of 65 and 84 years was identified from Medicare records. Sixty-six percent (2520 persons) agreed to undergo an eye examination; 26% of the participants were African American. The clinical examination included acuity testing with an Early Treatment Diabetic Retinopathy Study chart and standardized refraction testing for those with a visual acuity worse than 20/30, slitlamp and dilated retinal examination by an ophthalmologist, tonometry, lens and fundus photography, and a suprathreshold visual field test. Visual impairment was defined as a best-corrected acuity in the better-seeing eye worse than 20/40 and better than 20/200, while blindness was acuity in the better-seeing eye of 20/200 or worse. For those with a visual acuity worse than 20/40 in either eye, one or more causes were assigned by an ophthalmologist and a final cause for each eye was confirmed by a panel of 3 subspecialty ophthalmologists (O.D.S., H.A.Q., and S.B.B.) based on all available evidence. RESULTS: Bilateral presenting acuity worse than 20/40 increased from 4% in the 65- to 74-year age group to 16% in the 80- to 84-year age group. One third of those with presenting acuity worse than 20/40 improved to 20/40 or better with refraction. Overall, 4.5% had a best-corrected acuity worse than 20/40. African Americans were more likely to remain visually impaired than were whites despite refraction (odds ratio [95% confidence interval], 1.7 [1.1-2.6]). Whites were most often impaired or blind from age-related macular degeneration (1.2% vs 0.5%; P=.09). African Americans had higher rates of impairment and blindness from cataract or posterior capsular opacification (2.7% vs 1.1%; P=.006), glaucoma (0.9% vs 0.1%; P=.006), and diabetic retinopathy (1.2% vs 0.2%; P=. 004). CONCLUSIONS: More than half of those with visual impairment or blindness had conditions that were either surgically treatable or potentially preventable. African Americans had a disproportionate number of blinding diseases, particularly those amenable to eye care intervention. Targeted interventions for specific populations to increase appropriate eye care use would greatly improve vision and function in older Americans. Arch Ophthalmol. 2000;118:819-825

Exposure to sunlight and other risk factors for age-related macular degeneration.

As some ultraviolet (UV) radiation is transmitted by the ocular media, there is a growing concern that there may be a possible relationship between long-term exposure to ultraviolet radiation and increased risk of age-related macular degeneration. To address this question, a survey was conducted of 838 Maryland watermen who had well-characterized ocular UV-A and UV-B exposure. Fundus photographs were taken and graded for presence of exudative disease, geographic atrophy, focal hyperpigmentation of the retinal pigment epithelium, and drusen that were large and/or confluent. None of the subjects in these analyses were aphakic. The results suggested that age-related macular degeneration was not associated with cumulative exposure to either UV-A or UV-B. Age and the presence of nuclear opacity were independently associated with an increased risk of macular degeneration. Thus, we found that in phakic subjects, even with high levels of sunlight exposure, there was no evidence of increased risk of age-related macular degeneration associated with UV-B or UV-A exposure.

Macular scatter ('grid') laser treatment of poorly demarcated subfoveal choroidal neovascularization in age-related macular degeneration. Results of a randomized pilot trial.

OBJECTIVES: To determine the effects of macular scatter ("grid") laser photocoagulation compared with observation on the visual function of eyes with subfoveal choroidal neovascularization (CNV) that has poorly demarcated boundaries and to provide preliminary data for the evaluation of the feasibility and design of a larger, definitive trial. DESIGN: Randomized pilot clinical trial. SETTING: Two tertiary care retinal referral practices. PATIENTS: Symptomatic individuals with subfoveal CNV secondary to age-related macular degeneration in whom fluorescein angiography showed occult CNV with poorly demarcated boundaries; classic CNV was allowed but did not need to be present for entry into the study. MAIN OUTCOME MEASURE: Change in visual acuity from baseline to specified time periods. RESULTS: Fifty-two eyes were assigned to observation. Fifty-one eyes were assigned randomly to treatment consisting of macular scatter ("grid") laser photocoagulation to the area of CNV. The treatment protocol for 8 of these eyes also included confluent laser photocoagulation to areas of classic CNV. The average visual acuity decrease from baseline was greater in the treated than in the observed group. The difference between these groups was greatest within the first year after study enrollment. At 24 months, slightly more than 40% of the eyes in each group had lost 6 or more lines of visual acuity. Similar results were noted for the subgroup of eyes initially with angiographic features of occult CNV but no classic CNV. CONCLUSIONS: These short-term study results suggest that macular scatter ("grid") laser treatment is not beneficial and is possibly harmful compared with observation for symptomatic subfoveal CNV with poorly demarcated boundaries in age-related macular degeneration. With or without treatment, a significant proportion of these patients are at risk of severe visual loss within 2 years of seeking treatment, even when the eye initially has occult CNV and no classic CNV.

Occult choroidal neovascularization in age-related macular degeneration. A natural history study.

OBJECTIVE: To explore morphological and vision changes in untreated eyes with subfoveal choroidal neovascularization (CNV) that have poorly demarcated boundaries. DESIGN: Analysis of photographs of untreated patients with poorly demarcated occult CNV participating in a prospective clinical trial evaluating laser treatment compared with observation. SETTING: Two tertiary retinal referral centers. PATIENTS: Symptomatic individuals with poorly demarcated subfoveal occult CNV associated with age-related macular degeneration. MAIN OUTCOME MEASURES: Change in size of lesion, development of classic CNV, change in vision, and development of subretinal fibrosis. RESULTS: During follow-up (9-12 months), 32% of the occult choroidal neovascular lesions more than doubled their original size. Classic CNV developed in 52% of eyes that started without it. The median loss in visual acuity was 2.5 lines. Eyes with classic CNV or subretinal blood or both at baseline developed subretinal fibrosis more frequently and lost more visual acuity, but not to a statistically significant degree. CONCLUSIONS: The morphological changes of eyes with subfoveal occult CNV in which the boundaries are poorly demarcated in variable; the presence of subretinal blood or a component of classic CNV may influence the prognosis for further loss of vision.