Lens fluorophotometry after trabeculectomy in primary open-angle glaucoma.

OBJECTIVE: To evaluate the loss of lens transparency incurred by patients undergoing trabeculectomy. DESIGN: A prospective cohort study. PARTICIPANTS AND CONTROLS: Data corresponding to 33 eyes of 33 consecutive patients with primary open-angle glaucoma (POAG) subjected to trabeculectomy (group 1) were compared with those corresponding to 12 eyes of 12 patients with POAG receiving topical antiglaucomatous treatment (group 2). INTERVENTION: Lens fluorophotometry was performed on the group 1 patients before and 12 months after surgery. In group 2, fluorophotometry was conducted at the onset of the study and at 12 months of follow-up. MAIN OUTCOME MEASURES: Starting and final lens autofluorescence and transmittance values corresponding to each subject group were compared. RESULTS: In group 1, starting and final autofluorescence was 556.3 +/- 184.3 and 691.1 +/- 179.3 Eq ng/ml, and starting and final transmittance was 0.78 +/- 0.11 and 0.67 +/- 0.14, respectively. Respective values for group 2 were 574.3 +/- 94.8 and 595.2 +/- 107.0 Eq ng/ml and 0.72 +/- 0.17 and 0.71 +/- 0.16. The mean change between final and initial autofluorescence was statistically different between groups (134.7 +/- 123.7, group 1, 20.9 +/- 25.1 Eq ng/ml, group 2; P < 0.001). Similarly, a significant difference (P < 0.001) in transmittance change was observed between the surgery and control groups (-0.11 +/- 0.072, group 1; 0.02 +/- 0.008, group 2) CONCLUSIONS: It was demonstrated by lens fluorophotometry that trabeculectomy in POAG leads to a loss in lens transparency.     

Study of the crystalline lens by fluorophotometry in 60 control subjects and 56 diabetics]

Lens autofluorescence was measured with a commercially available computer fluorophotometer: Fluorotron Master, in 56 diabetic patients (34 insulin-dependent and 22 non insulin-dependent) mean age +/- S.E.M. = 45.65 +/- 3.92 years; and in 60 control patients, mean age +/- 44.82 +/- 4.70 years. Scanning measurement of fluorescence was performed along the optical axis of the two eyes. Lens fluorescence refers to the highest fluorescence intensity found in the anterior part of the lens nucleus: anterior lens peak. For both populations, lens autofluorescence increased linearly with age (p less than 0.001) and was significantly higher in the diabetic population at all ages. Statistical analysis revealed a significant correlation with the duration of diabetes for insulin-dependent (p less than 0.001) but not for non insulin-dependent diabetic subjects, and not on metabolic control: mean Hb A1C levels over last five years. These results showed that fluorophotometry was an objective and reproducible method for in vivo human lens study.     

Evaluation of diabetic retinopathy by fluorophotometry

Background: Fluorophotometric variables (permeability of the blood-retinal barrier (BRB) and blood-aqueous barrier (BAB), corneal autofluorescence, and lenticular light transmittance) are reported to correlate with the severity of diabetic retinopathy. This preliminary multicenter study was performed to measure these variables simultaneously in patients with type 2 diabetes mellitus and to assess which of these variables could be of help in evaluating diabetic retinopathy. Methods: Eighty-two patients with type 2 diabetes and diabetic retinopathy were recruited in seven European university clinics. Each patient was investigated three times, at intervals of about one year. The investigations included fluorophotometric determination of corneal autofluorescence, lenticular light transmittance, and permeability of the BRB and BAB. Retinopathy was classified into four grades, using a simplified evaluation system based on the Modified Airlie House retinopathy classification and applied to color fundus slides of standard fields 1 and 2. Results: Multiregression analyses revealed that only corneal autofluorescence and BRB permeability were correlated with the severity of diabetic retinopathy (P < 0.05). Corneal autofluorescence and BRB permeability as single variables were found to be indicative of severe nonproliferative retinopathy and proliferative retinopathy (sensitivity 100% and 86%, respectively, and specificity 65% and 85%, respectively). Combination of both variables increased specificity to 92%. Conclusions: This preliminary multicenter study shows that fluorophotometric variables can be measured simultaneously and reliably in patients with diabetes and that corneal autofluorescence and BRB permeability (individually or in combination) could be of help in detecting severe non-proliferative retinopathy and proliferative retinopathy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lens transmission of blue-green light in diabetic patients as measured by autofluorophotometry

Lens transmission for blue-green light (lambda = 490 nm and 530 nm) was assessed by means of fluorophotometry in 67 diabetic patients without cataracts and compared with that of 52 healthy controls. Lens transmission was determined from peak autofluorescence values in the anterior and posterior parts of the lens, assuming an about equal fluorescence peak quantum efficiency in both parts. The variation in lens transmission between individuals of about the same age was found to be larger in the diabetic patients than in the healthy controls. Decrease in lens transmission as a function of age occurred about 15 years earlier in patients with diabetes of more than 10 years' duration than in the healthy controls. The calculated average extra decrease of lens transmission in the diabetic group amounted to 0.5% for each year of diabetes.     

Vitreous fluorophotometric evaluation of diabetics

Vitreous fluorophotometry measurements taken from diabetic patients with different degrees of retinopathy and from normal volunteers were used to evaluate the integrity of the blood-ocular barrier. The contributions of lens and retinal fluorescence to the measured vitreous fluorescence were investigated. Lens autofluorescence was significantly higher for diabetics than for age-matched normals, and in age-matched diabetics the lens autofluorescence increased significantly with the progression of diabetic retinopathy. Natural ocular fluorescence was corrected for by subtracting baseline values from all vitreous measurements. Analysis of the baseline-corrected vitreous fluorescence values showed that both degree of retinopathy and age significantly affected the measured fluorescence. In age-matched groups, vitreous fluorescence values were greater in diabetics than in normals, and these values increased with the progression of retinopathy. Our results suggest that clinical vitreous fluorophotometry may be useful in evaluating the activity and predicting the progression of diabetic retinopathy.     

Ocular fluorophotometry in diabetic patients without apparent retinopathy

A fluorophotometer was remolded to gain high S-N ratio by photomultiplier cooling system, and ocular fluorophotometry of 65 diabetic patients without apparent retinopathy and 38 normal controls was performed. The mean fluorescein concentration one and two hours after intravenous dye injection, only lenticular autofluorescence in diabetics was significantly higher statistically, however, the variances were greater in the retina, the vitreous, and the anterior chamber. The rate of VF in the posterior vitreous more than M + 2 SD (the mean value and standard deviation of the normals) appeared significantly higher in diabetics. The case with abnormal posterior vitreous fluorophotometric value do not necessarily show the abnormal VF value in the anterior chamber. There were no significant difference statistically between the diabetic subgroups classified by the duration of the disease, metabolic control condition, associated hypertension of hyperlipemia, and the method of metabolic control.     

Lens autofluorescence and light scatter in relation to the lens opacities classification system, LOCS III.

PURPOSE: To compare values of the human lens autofluorescence and back light scatter measurements with the improved Lens Opacities Classification System, LOCS III. METHODS: We measured autofluorescence and back light scatter of the lens from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The retroillumination and slit-lamp photographs of the lenses were graded according to LOCS III by the Center for Ophthalmic Research in Boston. Lens fluorometry was carried out with a previously described technique using blue-green (495 nm/520 nm) autofluorescence range. Interzeag Lens Opacity Meter 701 was used for light scatter measurements. RESULTS: LOCS III nuclear opalescence and color grades were statistically significantly correlated with lens autofluorescence as well as with light scatter values. The lens transmission index of autofluorescence measurements showed the highest correlation with the nuclear color (r = -0.71; p < 0.0001) and the light scatter value with nuclear opalescence (r = 0.64; p < 0.0001). There was no correlation between autofluorescence measurements and LOCS III grades of cortical or posterior subcapsular cataract. A weak relation could be found between the grades of cortical cataract and light scatter values. CONCLUSIONS: The lens fluorometry provides a practical clinical technique to evaluate the yellow coloration and opalescence of the human lens nucleus. It may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.     

In vivo assessment of lens transmission for blue-green light by autofluorescence measurement

A simple quantitative and reproducible method for evaluating lens transmission (lambda = 490 and 530 nm) is described. It is based on the measurement of autofluorescence in the anterior and the posterior part of the lens by means of a fluorophotometer, assuming an about equal fluorescence quantum efficiency in both parts. Consequently any difference in fluorescence between both parts can be attributed to a loss of exciting and fluorescent light in the lens. For both wavelengths, the average lens transmission is determined by this method in a normal population as a function of age.     

Autofluorescence and light transmission in the aging crystalline lens

We quantitated blue-green light transmission and autofluorescence of the human crystalline lens in vivo, using an automated scanning fluorophotometer (Fluorotron) coupled with a lens system designed for high resolution of the ocular anterior segment. Lenses were scanned through the dilated pupil along the optical axis, generating a fluorescence profile consisting of anterior and posterior juxtacortical peaks and a central plateau. Fluorescence increased linearly with increasing age. We calculated percent transmission of excitation (410-500 nm) and emission (510-670 nm) as the ratio of posterior to anterior juxtacortical peaks. Light transmission decreased as a parabolic function of age and was correlated with both fluorescence increase and observed lens brunescence.     

Lack of fluorophotometric evidence of aqueous-vitreous barrier disruption after posterior capsulorhexis

PURPOSE: To evaluate the integrity of the aqueous-vitreous barrier by assessing the flow of fluorescein from the anterior chamber to the anterior vitreous using fluorophotometry in eyes with a posterior continuous curvilinear capsulorhexis (PCCC) and in eyes without a PCCC. SETTING: University Hospital Antwerp, Edegem, Belgium. METHODS: Ten patients had bilateral extracapsular cataract extraction with implantation of an intraocular lens. In 1 eye, a PCCC was performed; the other eye served as a negative control. The eyes of 2 other patients who had complicated cataract surgery with posterior capsule and anterior hyaloid membrane rupture served as positive controls. All patients had fluorophotometry of both eyes 12 to 18 months after surgery to measure the flow of fluorescein from the anterior chamber to the anterior vitreous. RESULTS: There were no statistically significant differences in the distribution pattern of fluorescein between eyes with PCCC and eyes without PCCC. In contrast, enhanced flow was detected in both eyes with rupture of the posterior capsule and the anterior hyaloid. CONCLUSIONS: In this fluorophotometry study, a PCCC did not seem to disrupt the aqueous-vitreous barrier. Results indicate that an intact anterior vitreous membrane is crucial to maintain the barrier function between the anterior and the posterior segments of the eye.     

Study of lens autofluorescence by fluorophotometry in pregnancy

Lens autofluorescence originates from an accumulation of fluorescent substances such as the tryptophan-derived residues and protein aggregations, which are associated with the preclinical progress of cataractogenesis, diabetes and lens aging. Our purpose is to determine if pregnancy alters the typical constituents of the lens autofluorescence. Fifteen healthy pregnant women (22 eyes) who were in their third trimester of pregnancy and 23 age-matched healthy controls (37 eyes, non-pregnant females). Lens autofluorescence, lens transmission and corneal autofluorescence were studied with fluorophotometry. The lens autofluorescence values were 358+/-151 ng ml(-1) in the control group and 201+/-110 ng ml(-1) in the pregnants women. The difference was significant (p=0.0074). Lens transmission values were 0.93+/-0.02 ng ml(-1) in the control group and 0.94+/-0.02 ng ml(-1) in the pregnants women: the difference was not significant. Corneal autofluorescence values were 21.9+/-7.5 ng ml(-1) in the control group and 18.2+/-5.8 ng ml(-1) in the pregnant women. The difference was not significant. Our study showed a significant decrease in lens autofluorescence in pregnant women compared to a normal population. The decrease can be partly attributed to the aqueous component of the lens that increases significantly during the final trimester of pregnancy and that this provokes a dilution of the fluorescent substances.     

Lens autofluorescence in healthy individuals

We measured blue-green autofluorescence (AF, 495 nm/520 nm) of the lens in 43 random eyes of 43 healthy volunteers aged 6-86 years, five in each decade, using an instrument designed by one of us (HN). The instrument generates an autofluorescence profile, which consists of anterior and posterior juxtacortical peaks and a central plateau. The height of the anterior peak was taken as a maximum autofluorescence value and the square root of the ratio between the posterior and the anterior peak was used as a lens transmission index. The coefficient of variation for the measurement technique was 3.9% for maximum autofluorescence and 2.9% for lens transmission index. Both the maximum autofluorescence and the transmission index were highly correlated with age. Statistically over 90% of the variation in maximum autofluorescence values and almost 70% of the variation in transmission could be attributed to age.     

Configuration of the normal vitreous fluorophotometry recording: Symbols

Findings during fluorophotometry studies of the normal human vitreous are described. The major landmarks are presented and a system of significant fluorophotometric variables is proposed. Use of this approach should optimize the evaluation of fluorophotometry data and maximize the information obtained concerning the status of the blood retinal barrier.A number of significant fluorophotometric variables should be characterized. We propose the following: posterior vitreous (PV), middle vitreous (MV), anterior vitreous (AV), lens (L), Anterior chamber (AC), gradient of posterior vitreous (GPV), gradient of anterior vitreous (GAV), blood-retinal barrier inward-transfer rate (BRB Kin), blood-retinal barrier outward-transfer rate (BRB Kout), and plasma (P).     

Ocular fluorophotometry in the normal- and diabetic monkey

Normal- and diabetic rhesus monkeys without retinopathy demonstrable by ophthalmoscopy or fluorescein angiography were examined with ocular fluorophotometry to detect alterations in their blood-ocular barriers. All vitreous fluorophotometry values were corrected for fluorescence attributable to background levels and then normalized to a blood fluorescein level of 10 micrograms ml-1. Reproducibility studies demonstrated an average coefficient of variation of 0.17 for all animals combined. Insulin-dependent monkeys, both pancreatectomized and streptozotocin-treated, demonstrated significantly higher posterior vitreous fluorescence levels than either control animals or monkeys treated with streptozotocin that were not insulin-dependent. These results cannot be attributed to differences in fluorescein binding or to vitreous abnormalities. However, 14 out of 24 (58%) of the insulin-dependent animals exhibited posterior vitreous fluorescence values within two standard deviations of the control mean. No correlation was apparent between the vitreous values and age or duration of treatment. No difference in anterior chamber concentrations was found between groups after correction. Our results indicate that alterations in blood-retinal barrier can occur in insulin-dependent diabetic monkeys before development of retinopathy.     

Is glaucoma associated with an increased risk of cataract?

AIMS--The risk of developing cataract in patients with untreated glaucoma or with ocular hypertension was evaluated by comparing the values of lenticular autofluorescence and light transmission in 16 patients with primary open angle glaucoma and 22 patients with ocular hypertension with those of 24 healthy controls. METHODS--Increase of lenticular autofluorescence and decrease of transmission values in comparison with controls were considered to be precursors of cataract. The values of both variables were determined by fluorophotometry. Each value was normalised for age by dividing it by the value for a healthy control of the same age. RESULTS--The mean age normalised autofluorescence and transmission values of all patients did not differ significantly from those of the controls (difference < 5%; p = 0.6 and p = 0.2, respectively). Also the mean age normalised autofluorescence and transmission values between glaucoma and ocular hypertension patients did not differ significantly (p = 0.8 and p = 0.9, respectively). CONCLUSION--The study indicates that untreated primary open angle glaucoma or untreated ocular hypertension do not seem to increase significantly the risk of developing cataract.     

Accommodation and presbyopia in the human eye--aging of the anterior segment

Ocular biometric parameters and accommodative amplitude were measured by various techniques in 100 normal emmetropic human subjects age 18-70 yr. Anterior chamber depth decreased and lens thickness increased linearly over the entire age group. Accommodative amplitude declined linearly until a stable nadir was reached at about age 50 yr. The respective slopes and intercepts of the age-dependent decline in anterior chamber depth were essentially the same for measurements made independently by optical pachmetry, A-scan ultrasonography, and slit-lamp Scheimpflug photography. The age-dependent increase in lens thickness differed in slope and intercept for measurements made by photography and ultrasonography if the generally accepted lenticular sound velocity was assumed for all subjects. However, if putative lenticular sound velocity was adjusted for age, the relationships given by the two techniques were essentially identical. Total anterior segment length (defined as the distance between the anterior corneal and posterior lens surfaces), vitreous cavity length (distance between the posterior lens and anterior retinal surfaces), and total globe length were all independent of age. This constellation of findings indicates that the human lens grows throughout adult life while the globe does not, that thickening of the lens completely accounts for shallowing of the anterior chamber with age, but that the posterior surface of the lens remains fixed in position relative to the cornea and retina.     

Changes in ocular dimensions and refraction with accommodation

The purpose of this study was to measure the changes in ocular dimensions with accom-modation, with particular reference to the radius of curvature of the posterior surface of the crystalline lens. The increase in power of the eye with accommodation is considered to arise primarily from a decrease in the radius of curvature of the anterior surface of the lens, with the role of the posterior surface somewhat unclear. We measured the axial dimensions (A-Scan ultrasonography), cornea1 radius of curvature (keratometryl, refractive error (auto-refractor) and radii of curvature of the lenticular surfaces (video phakometryl for 11 subjects, mean age 21.2 + 2.6 years, for five levels of ocular accommodation up to 8.00D. At maximum accommodation the mean changes were a decrease in anterior chamber depth of 0.24 mm. an increase in lens thickness of 0.28 mm. a decrease in radius of curvature of the anterior surface of the lens of 4.95 mm and 1.34 mm for the posterior surface. The corres-pondtng increase in power of the lenticular surfaces for an equivalent refractive index of 1.422 for the lens was 5.53 D and 3.10 D for the anterior and posterior surfaces respectively. No significant changes were recorded in axial length or vitreous chamber depth. We conclude that when crystalline lens power is calculated on the basis of an equivalent refractive index, changes in the posterior surface of the lens contribute around one third of the Increase in lens power associated with 8.00 D of ocular accommodation.     

Deposition of silicone oil droplets in the residual anterior lens capsule after vitrectomy and lensectomy in rabbits

AIM: To examine the histology of preserved anterior lens capsule in vitrectomised and lensectomised rabbit eyes with and without silicone oil tamponade. METHODS: Forty adult Japanese albino rabbits received two port vitrectomy and lensectomy with or without silicone oil tamponade in one eye under both general and topical anaesthesia. Anterior lens capsule was preserved during operation. After healing intervals residual anterior capsule was histologically observed under light or electron microscopy. RESULTS: Immediately after operation, cuboidal lens epithelial cells were observed on the posterior surface of the preserved anterior capsule. During healing intervals in eyes with or without silicone oil tamponade, regenerated lens structure of Sommerring's ring and fibrous tissue formed in the peripheral and central areas of the residual capsule, respectively. Ultrastructural observation revealed the presence of many vacuoles amid matrix accumulation on the posterior capsular surface, suggesting the deposition of emulsified silicone oil droplets. CONCLUSION: Lens epithelial cells produce regenerated lenticular structure and fibrous tissue on the residual capsule following vitrectomy and lensectomy in rabbits. Silicone oil droplets formed by its emulsification deposit in extracellular matrix accumulated on the posterior surface of the anterior capsule. Emulsified silicone may potentially enhance opacification of residual anterior capsule following pars plana vitrectomy by silicone oil deposition and subsequent activation of lens epithelial cells.     

Lens-induced astigmatism after perforating scleral injury

Within 6 weeks of a penetrating scleral injury that included vitreous prolapse, a 6-year-old boy developed lenticular astigmatism with a regular component of 5.5 diopters (D). Visible indentational folds in the posterior lens capsule, caused by anterior vitreous fibers and anterior hyaloid, were presumed to be the origin of the astigmatism. Because of decreased visual acuity and the suspicion of early amblyopia, a pars plana vitrectomy with removal of the anterior hyaloid and the critical anterior vitreous fibers was performed. Dense fibrotic tissue between the lens equator and the site of the original scleral perforation limited reduction of the preoperative astigmatism to 4.0 D. However, the striae-like lenticular deformation disappeared completely, and full visual acuity was restored. During the 12-month follow-up, the lens remained clear     

Quantitative analysis of lens changes after vitrectomy by fluorophotometry

We measured the amount of autofluorescence in the lens to evaluate quantitatively lens changes after vitrectomy. Thirteen phakic patients, ranging in age from 12 to 75 years, were studied after unilateral vitrectomy, with a follow-up period of more than two years (range, 26 to 55 months). Autofluorescence in the lens was measured at the center along the ocular axis by fluorophotometry. Lens autofluorescence in the eyes that underwent vitrectomy was significantly higher than in the contralateral eyes that were not operated on (P = .0003). The increase of autofluorescence was correlated significantly with the age at time of vitrectomy (P = .0008). There was no correlation between the increase in autofluorescence and the length of postoperative follow-up or the use of air during vitrectomy. Based on these results, we believe that oxidation of lens proteins intraoperatively may be one of the causes of development of nuclear cataract after vitrectomy.