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Aim: To assess foveal cone photoreceptor function in patients with unexplained loss of central visual acuity., Methods: Testing of foveal cone photoreceptor function was performed using scanning laser densitometry, colour matching (Rayleigh equation), and pattern electroretinography (ERG). Standard tests included full field ERG, electrooculography, visual evoked potentials, static perimetry, and fluorescein angiography., Results: Decreased foveal cone photopigment density and abnormal pattern ERG were found in three patients. Results of colour matching were not unequivocal., Conclusion: Testing of foveal cone photoreceptor function using scanning laser densitometry may determine the location of pathological changes in certain patients with unexplained visual loss.

Purpose: Fundus reflection densitometry was used as an objective means for monitoring the recovery of foveal cone photopigments in nine patients who underwent anatomically successful surgery of a rhegmatogenous retinal detachment with macular involvement., Methods: Postoperative assessment of foveal densitometry, visual acuity, color matching, and the Amsler grid were performed at repeated intervals for up to 14 months., Results: Gradual recovery of foveal cone photopigments was found in all patients 1 to 14 months after surgery, with considerable interindividual variation. Maximal recovery to values equalling those in the fellow eye was found in only one patient with a macular detachment duration of 5 days. All other patients had final photopigment densities below those of the fellow eye. The length of the preoperative detachment period was inversely related to the recovery of photopigment. The recovery of photopigment seems to increase further in the second year after surgery. Visual acuity increased rapidly in all patients during the first 6 months after surgery, to levels ranging between 20/67 and 20/25; thereafter, visual acuity did not change. A return to normal color matching after an episode of pseudoprotanomaly was found in four of nine patients, whereas pseudoprotanomaly remained in five patients. Complete resolution of metamorphopsia after surgery was seen only in the patient who had the shortest detachment duration. Metamorphopsia was consistent with decreased foveal cone photopigment densities., Conclusion: Foveal densitometry shows a slow recovery of the cone photopigments after reattachment, probably because of regrowth and realignment of the cone photoreceptor outer segments and metabolic recovery of the retinal pigment epithelium-cone photoreceptor complex. Recovery of photopigment, color matching, and metamorphosia follow a slower time course than recovery of visual acuity.

We compared the results of foveal densitometry with results of other retinal function tests in five asymptomatic subjects with adult-onset diffuse drusen. All results of routine retinal function tests, including visual acuity, Rayleigh equation color matches, multiple static perimetry, electroretinography, and electro-oculography, were normal. All five subjects had decreased foveal cone photopigment density with densitometry, indicating an early dysfunction at the level of the foveal cone photoreceptors. Several functional defects may be responsible for the densitometric results in adult-onset diffuse drusen, including retinal pigment epithelium dysfunction, foveal cone photoreceptor misalignment, and a reduction of the in situ foveal cone photopigment.

We describe a family with an as yet undescribed form of X-linked progressive cone dystrophy in a five-generation pedigree, from which we report here the results of 17 male patients and 31 obligate and 13 possible female carriers. The affected males showed the characteristic picture of cone dystrophy. Foveal cone photopigment density was impaired (judged from anomaloscope settings and foveal densitometry), even at an early stage of the disease. The carriers showed no fundus abnormalities, except occasional changes due to myopia. The anomaloscope demonstrated mild pseudoprotanomaly in 27 of 31 obligate carriers and in six of 13 possible carriers. Foveal densitometry findings performed in 11 carriers always agreed with the anomaloscope findings. We conclude that the findings of pseudoprotanomaly and abnormal density differences in females of this family were the only ocular abnormalities and thus are indicative of the carrier state.

We investigated foveal cone photopigment kinetics by retinal densitometry in 34 eyes of 29 healthy subjects with clear optical media and good visual acuity, ranging in age from 39 to 79 years. Our aim was to assess possible senile disturbances of foveal cones. To assess the effects of ocular straylight, we measured not only in subjects with a clear crystalline lens, but also in pseudophakia and aphakia. In a limited number of subjects color vision was assessed with a Nagel anomaloscope; no systematic changes with age were found. A significant decrease in two-way density and in time constant of regeneration was found to occur only after age 60, with large individual variations. There was no indication that results for subjects with their natural crystalline lens, in aphakia, or in pseudophakia were different. We argue that a reduction in the number of cones with age, rather than an increase in ocular stray light is the most likely explanation of our findings.