Optimal time following fluorescein instillation to evaluate rigid gas permeable contact lens fit.

PURPOSE: To examine the optimum time at which fluorescein patterns of gas permeable lenses (GPs) should be evaluated. METHODS: Aligned, 0.2mm steep and 0.2mm flat GPs were fitted to 17 patients (aged 20.6 ± 1.1 years, 10 male). Fluorescein was applied to their upper temporal bulbar conjunctiva with a moistened fluorescein strip. Digital slit lamp images (CSO, Italy) at 10× magnification of the fluorescein pattern viewed with blue light through a yellow filter were captured every 15s. Fluorescein intensity in central, mid peripheral and edge regions of the superior, inferior, temporal and nasal quadrants of the lens were graded subjectively using a +2 to -2 scale and using ImageJ software on the simultaneously captured images. RESULTS: Subjectively graded and objectively image analysed fluorescein intensity changed with time (p < 0.001), lens region (centre, mid-periphery and edge: p < 0.05) and there was interaction between lens region with lens fit (p < 0.001). For edge band width, there was a significant effect of time (F = 118.503, p < 0.001) and lens fit (F = 5.1249, p = 0.012). The expected alignment, flat and steep fitting patterns could be seen from approximately after 30 to 180 s subjectively and 15 to 105 s in captured images. CONCLUSION: Although the stability of fluorescein intensity can start to decline in as little as 45 s post fluorescein instillation, the diagnostic pattern of alignment, steep or flat fit is seen in each meridian by subjective observation from about 30s to 3 min indicating this is the most appropriate time window to evaluate GP lenses in clinical practice.

Fluorophotometry to evaluate the corneal epithelium in eyes undergoing contact lens corneal reshaping to correct myopia.

PURPOSE: To determine whether use of Corneal Refractive Therapy (CRT, Paragon Vision Sciences) lenses have an adverse effect on the health of corneal epithelium by monitoring epithelial permeability by fluorophotometry. METHODS: Eight patients with healthy eyes and whose refractive error was between -0.50 and -4.00 diopters (D) sphere and up to -1.75 D of astigmatism were enrolled. On the day of the fitting, two baseline fluorometric scans of the right eye were taken using the Ocumetrics Fluorotron Master. After 15 minutes, another two scans were taken of the right eye. The same fluorophotometry technique was repeated on day 1, 1 week, 1 month, and 3 months after the patient began overnight wear of the lenses. Patients' baseline corneal fluorescein levels and peak corneal fluorescence values after rinsing were compared to initial pre-fitting values to determine changes in corneal epithelial permeability. RESULTS: After patients used orthokeratology, uncorrected visual acuity was 20/20 or better in 9/16 eyes and 100% had achieved 20/40 or better by day 7. No adverse events were seen in patients utilizing orthokeratology, and eye examinations for these patients continued to be within normal limits. After nightly use of orthokeratology for 1 month, baseline fluorescence of the cornea (15.64 +/- 2.29 ng/mL vs 17.31 +/-5.43 ng/mL, P = .80) remained stable, and the post-15 minute scan peak corneal fluorescence values did not show significant changes from the pre-fitting (51.46 +/- 17.28 ng/mL) after use of orthokeratology (63.80 +/- 41.25 ng/mL) (P = .78). CONCLUSIONS: Reshaping of the cornea through the use of orthokeratology does not have adverse effects on corneal epithelium as evaluated by changes in corneal epithelial permeability.

[Vitreal fluorometry]. / Fluorofotometria vitrosului.

Vitreous fluorophotometry is an investigation that facilitates the quantitative study of the blood-retinal barrier (thus allowing a better understanding of its physiopathology and opening new therapeutical research fields). It can be performed for the vast majority of the ocular diseases: diabetic retinopathy, arterial hypertension, uveitis, post-cryotherapy/laser photocoagulation, retinal vascular diseases, choroidal melanoma, optic nerve diseases etc.

Adenosine agonist regulation of outward active transport of fluorescein across retinal pigment epithelium in rabbits.

To investigate the effect of an adenosine agonist, 2-5'-N-ethylcarboxamidoadenosine (NECA), on the outward active transport of fluorescein across the retinal pigment epithelium (RPE) in rabbits. High (5x10(-4)-2x10(-3) M) and low (1x10(-5)-1x10(-4) M) concentrations of NECA or phosphate buffered saline (PBS) were intravitreously injected into Dutch-belted rabbits. Sodium fluorescein was injected intravenously 180 min after NECA. Differential vitreous fluorophotometry was performed 3 hr after the sodium fluorescein injection and the vitreal fluorescein/fluorescein monoglucuronide (F/FG) ratio then was calculated. The F/FG ratios are inversely proportional to the outward active transport of fluorescein across the RPE. Retinal detachments were induced by injection of PBS into the subretinal space after the intravitreous injection of low- or high-dose NECA or PBS, and the size of the blebs was monitored. In eyes that received a low-dose injection of NECA, the F/FG ratio was higher compared with controls (P<0.05); in eyes that received a high-dose intravitreal injection, the F/FG ratio was significantly lower compared with controls (P<0.05). The effect of low-dose NECA on the F/FG ratio was suppressed by the A2 receptor antagonist, ZM241385, and the effect of high-dose NECA was suppressed by the A1 receptor antagonist, 8-cyclopentyl-1, 3-dipropylxanthine. The A3 receptor antagonist MRS1191 did not influence the effect of low- or high-dose NECA. Intravitreal injection of high-dose NECA enhanced the reabsorption of subretinal fluid compared with PBS; however, low-dose NECA inhibited reabsorption of subretinal fluid (P<0.02 and 0.05, respectively). Intravitreous injection of high-dose NECA accelerates the active outward transport across the RPE via A1 receptors and low-dose NECA decelerates it via A2 receptors.

[A novel fluorophotometric method for assaying free glutathione of both reduced and oxidized in plasma].

To investigate the measurement of free glutathione of both reduced or oxidized (i.e. GSH and GSSG) in plasma, and to evaluate the redox state of GGSH/GSSG in human plasma, both GSH and GSSG in plasma were measured by fluorophotometry based on the facts that one molar GSSG can be reduced to two molar GSH by dithiothreitol(DTT) under the condition of the pH being about 6.0, and GSH can provide both primary amine and thiol groups to react with the two carbonyl groups of O-phthaldehyde (OPA) to form a fluorescent ternary isoindole complex at pH 8.0. This method can at least measure 16 picomole GSH and 8 picomole GSSG respectively in the tube. The variation coefficient (CV) for intra-ssay and intera-ssay is about 4. 6% and 3.9% for GSH and 3.5% and 4.1% for GSSG respectively. The recovery of GSH and GSSG added to the plasma is (99.77% +/- 5.70)% and (99.28% +/- 4.73)% respectively. The concentration of GSH and GSSG in the plasma of young healthy volunteer is (16.5 +/- 2.4) nmol x mL(-1) and (1.7 +/- 0.35)nmol x mL(-1) respectively, without significant difference between male and female. This measurement method is simple with great sensitivity and selectivity for rapid measuring GSH and GSSG in human plasma simultaneously.

Determination of the aqueous humor volume by three-dimensional mapping of the anterior chamber.

In this study involving 12 patients planned for routine cataract surgery, we used the topography of the anterior chamber depth and the corneal diameter obtained from Orbscan II data to calculate the aqueous humor volume. Prior to the surgical procedure, a small amount of fluorescein was injected into the anterior chamber and an aqueous humor sample was taken, from which the aqueous humor volume could be calculated by fluorometry. The volumes obtained from Orbscan II data were validated by the fluorometric measurements and compared to three theoretical formulas for aqueous humor volume calculation. The aqueous humor volume calculations based on the Orbscan II data aligned better to the fluorometric values (R(2) = 0.890) than the values obtained by Heim's formula (R(2) = 0.677), Brubaker's formula (R(2) = 0.671), and Schenker's formula (R(2) = 0.585), or the assumption of a constant aqueous humor volume.

[Study of direct fluorophotometric and flow-injection fluorophotometric methods based on the inhibitory effect for the determination of trace formaldehyde].

Sulfite reacts with o-phthalaldehyde in the presence of ammonium forming the highly fluorescing isoindole-1-sulfonate in neutral or weakly acid solution, and formaldehyde has inhibitory effect on it. Based on this principle, the authors developed the direct fluorophotometric and flow-injection fluorophotometric methods for the determination of trace formaldehyde. The maximum excitation wavelength and the maximum emission wavelength are 320 and 390 nm respectively. With the direct fluorophotometric method, formaldehyde in the concentration range of 0.10-1.60 microg x mL(-1) can be determined with a detection limit of 0.046 microg x mL(-1). With the flow-injection fluorophotometric method, formaldehyde in the concentration range of 0.10-2.00 microg x mL(-1) can be determined with a detection limit of 0.085 microg x mL(-1). The methods were applied respectively to the analysis of river water with satisfactory results.

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.

Nitric oxide levels in aqueous humor after lens extraction and poly(methyl methacrylate) and foldable acrylic intraocular lens implantation in rabbit eyes.

PURPOSE: To measure the nitric oxide (NO) level in the aqueous humor of rabbit eyes after common cataract surgery techniques. SETTING: Department of Ophthalmology, Military Medical University, and Department of Immunology and Immunotoxicology of Respiratory System, Clinic of Pneumonology and Allergology, Medical University of Lódz, Lódz, Poland. METHODS: Thirty rabbits were randomly divided into 4 groups, and surgery was performed as follows: Group 1, extracapsular cataract extraction (ECCE) and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation; Group 2, ECCE; Group 3, phacoemulsification and foldable acrylic IOL implantation; Group 4, phacoemulsification. The aqueous humor specimens were collected on days 1, 3, and 5. Nitric oxide measurements were performed indirectly with a spectrophotometer. The NO level in the aqueous humor collected before surgery served as a control group. RESULTS: In the physiological condition, the concentration of NO was 26.52 nm/dL +/- 4.86 (SD). Postoperatively, the highest NO level in each groups was as follows: Group 1, 46.26 +/- 5.23 nm/dL on day 3; Group 2, 72.46 +/- 6.94 nm/dL on day 1; Group 3, 41.04 +/- 7.31 nm/dL on day 1; and Group 4, 32.67 +/- 2.84 nm/dL on day 3. Significantly higher levels of NO (P <.05) were observed in Groups 1 and 2 at each follow-up day; in Group 3, on days 1 and 3; and in Group 4, on day 3. CONCLUSIONS: Techniques of cataract extraction caused the NO level to increase; however, phacoemulsification with a foldable IOL caused the smallest release of NO. Rapid postoperative NO changes may theoretically contribute to blood-aqueous barrier breakdown secondary to cataract surgery.

Novel noninvasive sensitive determination of tear volume changes in normal cats.

We describe a novel, high-resolution and noninvasive method for measuring tear volume changes in cats. The method entails photographing at the lid margin the tear meniscus area defined by instillation of 0.1% fluorescein solution into the cul-de-sac. The inferior tear meniscus area was obtained from the digitized images with computer-assisted software. The tear meniscus area increased in proportion to the saline volume applied into the conjunctival sac, which validates the technique. Furthermore, this technique detected with high sensitivity previously described increases in tear fluid secretion induced by the P2Y(2) agonist. We demonstrate in cats that changes in conjunctival sac tear volume can be evaluated by measurement of its inferior tear meniscus area.

Diabetic macular oedema: a comparison of vitreous fluorometry, angiography, and retinopathy.

AIM: To evaluate the relation between the quantitative measurement of vitreous fluorescein with fluorescein angiography and retinopathy in diabetic patients with and without clinically significant macular oedema (CSMO). METHODS: In a prospective cross sectional study, passive permeability and active, outward transport of fluorescein across the blood-retinal barrier were quantitated with vitreous fluorometry in 61 eyes from 48 patients with CSMO and 22 fellow eyes without CSMO, after exclusion of eyes with previous macular laser treatment and vitreous liquification. All patients were recruited from the university hospital's outpatient clinic. Retinopathy and fluorescein angiograms were evaluated on 60 degree photographs. RESULTS: The passive permeability in CSMO was significantly correlated with the severity of leakage on fluorescein angiograms (r=0.73), the level of retinopathy (r=0.61), and visual acuity (r=0.45). Significant differences between eyes with CSMO and eyes without CSMO were found for passive permeability (p<0.001), fluorescein leakage (p<0.001), visual acuity (p=0.02), and retinopathy (p=0.002). CONCLUSION: Passive permeability of fluorescein quantitated with vitreous fluorometry was correlated both with semiquantitative fluorescein angiography and retinopathy, and a significant increase in passive permeability was found when comparing eyes with CSMO to eyes without CSMO. No such pattern was found for the active transport indicating that passive and not the outward, active transport is the factor of most importance in the development of CSMO.

Corneal autofluorescence in choroidal melanoma or in choroidal naevus.

AIMS: To investigate whether corneal autofluorescence is different in patients with choroidal melanoma or choroidal naevus. METHODS: Corneal autofluorescence was determined by fluorophotometry in both eyes of 32 patients with a unilateral choroidal melanoma, 32 patients with a unilateral choroidal naevus, and 32 age matched healthy controls. The corneal autofluorescence ratio between affected and contralateral eyes of patients or between randomly selected eyes of healthy controls was calculated. RESULTS: Mean corneal autofluorescence ratio of patients with a choroidal melanoma was significantly higher than that of healthy controls (mean ratio: 1.09 (SD 0.15) and 1.00 (0.09), respectively, ANOVA p=0.014), and than that of patients with choroidal naevus (mean ratio 0.96 (0.09), p<0.001). Mean ratios of patients with choroidal naevus and healthy controls were not significantly different (p=0.27). CONCLUSIONS: Corneal autofluorescence ratio of patients with a unilateral choroidal melanoma is increased. This is probably due to an increased flow of glucose through the impaired blood-aqueous barrier in the affected eye, resulting in additional glycation of corneal proteins and hence in increased autofluorescence. The corneal autofluorescence is not increased in patients with a choroidal naevus, because the blood-aqueous barrier is not impaired in the affected eye in these patients. Measurement of corneal autofluorescence is simple, fast, and non-invasive, and might be helpful to distinguish between patients with choroidal melanoma and those with choroidal naevus.

[The function of corneal endothelium after penetrating keratoplasty as measured with fluorophotometry]. / Funkcja sródblonka rogówki po keratoplastyce drazacej w ocenie fluorofotometrycznej.

The aim of the study was to calculate the corneal endothelial permeability (Pac) 12 and 18 months after penetrating keratoplasty in patients (aged 42-60 years) with very good prognosis for graft clarity (10 eyes with pseudophakic and 4 eyes with aphakic bullous keratopathy; 6 eyes with keratoconus; 2 eyes with granular dystrophy; 6 eyes with central inactive scars; 1 eye with early central Fuchs' dystrophy). The normal eyes (10 eyes) served as control group in persons aged 40-65 years. Each operated eye was submitted to fluorophotometry of the anterior segment with measurement of corneal endothelial permeability (Fluorotron Master, Coherent) 12 and 18 months after the surgery. The cornea thickness measurement and endothelial cell counting were performed by specular microscopy with pachymeter 12 and 18 months after penetrating keratoplasty in cases with very good prognosis for graft clarity. The mean values of Pac: 4.48 x 10(-4) +/- 1.24 cm/min after 12 months were significantly higher (p < 0.05) than in the control group (3.61 x 10(-4) + 0.51 cm/min). Neither significant changes in corneal thickness nor endothelial cell density were noted as a result of surgery. The calculation of Pac in a late period after penetrating keratoplasty revealed a stable partial exhaustion of the corneal endothelium function in cases with good prognosis for graft clarity.

Correlation of tear fluorescein clearance and Schirmer test scores with ocular irritation symptoms.

OBJECTIVE: To correlate and compare the Schirmer 1 test and a new method of measuring tear fluorescein clearance with the CytoFluor II fluorometer with the severity of ocular irritation symptoms, clinical signs of meibomian gland disease, corneal fluorescein staining scores, and corneal and conjunctival sensitivity. DESIGN: Case-control study. PARTICIPANTS: Forty patients presenting with a chief complaint of ocular irritation, and 40 asymptomatic control subjects of similar age distribution. INTERVENTION: All subjects completed a symptom questionnaire, a baseline ocular examination, fluorescein clearance test (FCT), and Schirmer 1 test. MAIN OUTCOME MEASURES: The FCT was performed with a CytoFluor II fluorophotometer by measuring the fluorescein concentration in minimally stimulated tear samples collected from the inferior tear meniscus 15 minutes after instillation of 5 microl of 2% sodium fluorescein. Severity of ocular irritation was assessed with a symptom questionnaire. Schirmer 1 test, biomicroscopic meibomian gland evaluation, corneal fluorescein staining score, and corneal and conjunctival sensation scores were assessed with the Cachet-Bonnet anesthesiometer in all subjects. RESULTS: Irritation symptoms correlated with higher log tear fluorescein concentration (symptomatic 3.08 +/- 0.62 units/,microl, normal control 1.89 +/- 0.7 units/microl, P < 0.005) and lower Schirmer 1 test scores (symptomatic 12.6 mm, normal control 22.3 mm, P < 0.005). The FCT showed greater predictive value for identifying ocular irritation than the Schirmer 1 test. A fluorescein concentration of 274 units//microl eliminated 80% of the normal subjects (specificity) and identified 85% of the abnormal subjects (sensitivity). Log of tear fluorescein concentration and the Schirmer 1 test correlated with meibomian gland orifice metaplasia (2.81 +/- 0.78 units/microl and 14.47 +/- 9.53 mm in those with metaplasia vs. 1.83 +/- 0.71 units/microl and 23.14 +/- 7.67 mm in those without metaplasia, P < 0.001) and with the percentage of acinar dropout. Both log of tear fluorescein concentration and the Schirmer 1 test correlated with corneal fluorescein staining (Pearson correlation of 0.394 P < 0.0001 for Schirmer 1 test and 0.312 P < 0.005 for log of tear fluorescein). In addition, log of tear fluorescein and Schirmer 1 test scores correlated with corneal and conjunctival sensation scores (Spearman's rho for corneal sensation: log of tear fluorescein -0.38, P < 0.003, Schirmer 1 test -0.39, P < 0.002, and for conjunctival sensation: log of tear fluorescein -0.391, P < 0.001, Schirmer 1 test -0.23, P < 0.061). CONCLUSIONS: The FCT shows a greater predictive value for ocular irritation than the Schirmer 1 test. It correlates better with age, meibomian gland dysfunction, and decreased corneal and conjunctival sensation. Decreased tear clearance was identified as a risk factor for ocular irritation, even in subjects with normal Schirmer scores. This simple technique may provide new clues into the mechanism and therapy of ocular irritation.

Aqueous flare in patients with monocular iris atrophy and uveitis. A laser flare and iris angiography study.

PURPOSE: To study aqueous flare longitudinally in patients with Fuchs' heterochromic uveitis (FHU) and for comparison in another group with iris atrophy (non FHU). METHODS: A new laser flare meter was used. Iris angiography was performed in most FHU patients. RESULTS: The flare values in the affected eyes in the FHU group were always higher compared to the normal eyes and rather constant over time. Cataract surgery did not permanently change the flare values. Systemic - but not local steroid therapy caused normalization of the flare. Iris angiography displayed leakage in all FHU eyes. Leakage from original vessels dominated although some newly-formed leaking vessels were observed. CONCLUSIONS: The results support the notion that FHU is a low grade, chronic, stable disease. Leaking iris vessels, original or newly-formed, are probably the source of the increased flare. Our hypothesis is that inflammation plays a major part. Atrophy per se does not enhance flare.

Prolonged impairment of peripheral corneal epithelium barrier function after successful trabeculectomy.

PURPOSE: To quantitate changes in the ocular surface after trabeculectomy using a newly designed fluorophotometer-based method. METHODS: We studied 23 normal eyes (23 volunteers), six eyes (six patients) within 1 month after surgery (early group), and 14 eyes (14 patients) 3 months or longer after surgery (late group). Also, to elucidate time-dependent changes in corneal epithelium barrier function, we measured fluorescein uptake before and after trabeculectomy prospectively in the central and peripheral cornea of six glaucomatous eyes in six patients. RESULTS: Mean fluorescein uptake (+/- SE) in the central cornea 30 minutes after instillation was 34.4 +/- 3.8 ng/ml, 113.5 +/- 65.8 ng/ml, and 43.1 +/- 12.8 ng/ml, respectively, in the normal, early, and late groups, which represents a statistically significant increase in the early group, but subsequent recovery to near normal range in the late group (P = .0225, normal vs early groups; P = .437, normal vs late groups, unpaired t test). Mean fluorescein uptake in the peripheral cornea was 34.5 +/- 6.1 ng/ml, 276.2 +/- 120.5 ng/ml, and 378.4 +/- 118.2 ng/ml, respectively, in the normal, early, and late groups, which represents a statistically significant increase in both the early and late groups (P = .0267, normal vs early groups; P = .0310, normal vs late groups, unpaired t test). In the early and late groups, significant differences were shown in fluorescein uptake between the central and peripheral cornea, but these differences were not evident in the normal group. The prospective study showed that fluorescein uptake in the peripheral cornea was 35.3 +/- 13.0 ng/ml and increased to 308.2 +/- 96.6 ng/ml at the third postoperative month (P = .022, paired t test) and to 277.9 +/- 145.5 ng/ml at the end of the first postoperative year (P = .154, paired t test). CONCLUSION: Peripheral corneal epithelium barrier function adjacent to the filtration bleb following trabeculectomy may be significantly impaired for at least 1 year after surgery.

Evaluation of the lacrimal drainage function by the drop test.

PURPOSE: To compare the fluorescein dye disappearance test with a new test for lacrimal drainage capacity, the drop test. METHODS: In the fluorescein dye disappearance test, 1 microliter of fluorescein solution was instilled into the conjunctival sac of normal subjects and of patients with epiphora. Fluorescence from the tear film was measured, and the rate of dye disappearance was calculated as a measure of tear drainage. In the drop test, drops of 10 microliters of lukewarm saline solution were repeatedly instilled into the conjunctival sac for 3 minutes. Excessive saline solution was then removed from the tear film and measured. The volume of saline solution drained by the lacrimal passage could thus be calculated. RESULTS: The fluorescein dye disappearance test showed, in normal subjects, a tear turnover rate of 10.9 +/- 3.1% (95% confidence interval) per minute, which was nor age dependent. The drop test showed a decreased lacrimal drainage capacity with increasing age in normal subjects, with a mean capacity of 150 +/- 38.5 microliters/3 min for those 41 to 80 years old. In patients with indoor epiphora, the fluorescein dye disappearance test values were significantly reduced. However, the fluorescein dye disappearance test could not differentiate among normal eyes, eyes with minor epiphora, or eyes with moderate epiphora. The drop test showed a significant decrease even in patients with minor epiphora and was further decreased with increasing severity of symptoms. CONCLUSION: The drop test provides a quantitative measurement for lacrimal drainage function and is more sensitive than the fluorescein dye disappearance test.

Comparative study of three methods of evaluation of the corneal endothelium in pseudophakic patients: fluorophotometry, specular microscopy and pachymetry.

BACKGROUND: At present, three techniques, based on different methodological suppositions, are used indiscriminately for the study of the corneal endothelium. These are pachymetry, specular microscopy and fluorophotometry. The purpose of this work was to study the corneal endothelium of pseudophakic patients with the three techniques mentioned. On the basis of the results obtained, we discuss the relations between them and their practical clinical utility. METHODS: One hundred and fourteen eyes of pseudophakic patients were studied using the three corneal endothelial evaluation techniques, both in the immediate pre-operative period and 1 year after surgery. RESULTS: Statistically significant relations exist between the number of endothelial cells and the fluorophotometric endothelial permeability coefficient (Kc.ca) 12 months after surgery, between the increase in corneal thickness in the first week after the operation and the Kc.ca 12 months after surgery, and between fluctuations of the corneal thickness greater than 30 microns and both the endothelial cell count and the Kc.ca 12 months after surgery. There are no significant relationships among the pre-operative values obtained with the three methods. CONCLUSION: The results show how the parameters measured with the functional techniques (fluorophotometry, pachymetry) generally become normal after the surgical trauma, while the endothelial cell count remains irreversibly altered. The results obtained with different techniques are more closely related in more pathological endothelia, while no relation among them are shown in the study of normal endothelia. It is also shown how pachymetry is a good clinical predictor, in the immediate post-operative period, of the long-term status of the corneal endothelium.

Corneal metabolism and epithelial barrier function after cataract surgery and intraocular lens implantation: a fluorophotometric study.

PURPOSE: The aim of this study was the assessment of possible changes in corneal metabolism and epithelial barrier function after an extracapsular lens extraction with artificial lens implantation. METHODS: Ten patients without any eye medication were selected out of 140 patients attending for extracapsular lens extraction with lens implantation at the university hospital. Corneal metabolism was evaluated by fluorophotometric measurement of corneal autofluorescence. The corneal fluorescence values were corrected for interference by the fluorescence of the ocular lens. Corneal epithelial barrier function was evaluated by determination of corneal epithelial permeability. The permeability was calculated from the fluorescein penetration into the cornea after application of an eye bath containing fluorescein. Operated and fellow eyes were investigated 1 week before and 3-4 weeks after the operation. RESULTS: The corneal autofluorescence of the operated eye decreased significantly after surgery (mean decrease: 14%, Wilcoxon paired-sample test: P = 0.038). The corneal epithelial permeability of both eyes increased after surgery above the normal range of healthy controls (mean increase operated eye: 34%, P = 0.015, fellow eye: 32%, P = 0.15). Both corneal autofluorescence and epithelial permeability returned to normal values after one year. CONCLUSIONS: The lower corneal autofluorescence in the operated eye after surgery indicates a lower corneal metabolism which may be due to surgery. The increased epithelial permeability of both eyes implies a temporary impairment of the corneal barrier function. The interaction with the fellow eye indicates a consensual reaction which may attributed to damage to the neural system by the surgery.