[The cornea in high axial myopia]. / Cornée et myopie axile forte.

PURPOSE: To compare corneal characteristics of eyes with high myopia with those of eyes with no spherical ametropia using Orbscan and ultrasonic pachymetry. METHODS: Orbscan and ultrasonic pachymetry values were prospectively recorded in a study group of 105 patients with high myopia (i.e., axial length greater than 26mm in both eyes) and in a control group of 105 patients with no spherical ametropia (absolute value of spherical equivalent less than 1.25D regardless of cylinder value). Astigmatism data were expressed by rectangular coordinates in a dioptric plane. Axis was decomposed in 2 components (WTR/ATR and oblique) which were analyzed by Cos2axis and Sin2axis trigonometric functions. Enantiomorphism (mirror-image symmetry) between fellow eyes was quantified by a Euclidean distance for the location of the thinnest point and by the difference (in absolute value) between 180° and the sum of both axes for astigmatism. RESULTS: In the study group, the mean axial length and subjective spherical equivalent were, respectively, 27.82±2.14mm (26.00 to 34.06) and -9.00±3.46D (-4.71 to -19.82). The mean corneal astigmatism was +0.92D×91.3° in the study group and +0.65D×89.3° in the control group. The mean corneal cylinder was higher in the study group (1.44D versus 0.91D; P<0.001) whereas axis showed no significant differences between both groups. The mean maximal keratometry was steeper in the study group (44.53D versus 44.13D; P=0.03) whereas the mean keratometry and minimal keratometry displayed no significant differences between both groups. No significant differences in central corneal thickness (540.2µm versus 546.9µm; P=0.10), peripheral corneal thickness, corneal diameter, corneal irregularity, asphericity, and irregular astigmatism were found between both groups. There were no significant differences in enantiomorphism parameters between both groups. In the study group, correlation with axial length was significant only for spherical equivalent (r=-0.86; P<0.001) and corneal cylinder (r=0.16; P=0.04). CONCLUSION: High myopia exhibits corneal characteristics similar to corneas of eyes with no spherical ametropia, except for toricity. While the posterior segment elongates, development of high myopia appears not to affect corneal characteristics. Corneal toricity may be associated with evolution toward high myopia by perturbing mechanisms of emmetropization.

[Relationships between refractive parameters: sphere, cylinder and axis]. / Relations entre les paramètres de la réfraction : sphère, cylindre et axe.

PURPOSE: To analyze the relationships between refractive parameters as well as the relationship between fellow eyes in a normal population. METHODS: Both subjective refraction and auto-refractometry data of 500 patients were prospectively recorded. Refraction data were analyzed on three rectangular coordinates in a dioptric space. WTR/ATR ratio of axis was quantified by the Cos2axis function. Enantiomorphism (mirror-image symmetry) between fellow eye axes was quantified by the absolute value of the difference between 180° and the sum of both axes. RESULTS: Mean refraction and mean cylinder were -1.74D (+0.28D × 91.5°) and 0.81 ± 0.89D respectively. The spherical component had no significant influence on refractive astigmatism (r(s)≤ 0.07, P ≥ 0.07) except for high spherical ametropia. Eyes with spherical equivalent greater than 4D (in absolute value) demonstrated higher cylinder (1.15D vs 0.84D, P<0.001). Cylinder influenced the WTR/ATR ratio (r(s)=-0.25, P<0.001) and the enantiomorphism (r(s)=0.36, P<0.001). Age also influenced the WTR/ATR ratio (r(s)=0.27, P<0.001) and the enantiomorphism (r(s)=0.14, P<0.001). Axes were more likely WTR and enantiomorphic when the cylinder was high and the subject young. Oblique axes were less enantiomorphic (35.5° vs 20.6°, P<0.001) and were associated with lower cylinder (0.56D vs 0.98D, P<0.001). Correlation between fellow eyes was significant for cylinder (r(s)=0.66, P<0.001) and for spherical equivalent (r(s)=0.96, P<0.001). Gender had no significant influence on refraction (P>0.12) except for spherical equivalent (relative hyperopia of +0.17D, P=0.04 in females). CONCLUSION: The spherical component of the refraction appears to be independent of the refractive astigmatism except for high spherical ametropia. Cylinder influences somewhat the WTR/ATR ratio of axis and the enantiomorphism. Relationships between refractive parameters are weak in comparison to the fellow eye relationships.

[Fungal keratitis caused by Cylindrocarpon lichenicola]. / Kératite fongique à Cylindrocarpon lichenicola.

We report a case of a 67-year-old woman with no significant past ocular history, who was referred for management of an unresponsive microbial keratitis resulting from trauma with a piece of clothing fabric 1 month previously in Portugal and worsening despite topical fortified antibiotics. On examination, visual acuity was limited to "light perception". Slit lamp examination revealed an 11×11mm full-thickness corneal infiltrate. Confocal images showed branching hyphae suggestive of a fungal infection. Fungal cultures of corneal scrapings revealed growth of Cylindrocarpon lichenicola, a saprophytic, filamentous fungus, which is an unusual cause of keratitis. Despite aggressive antifungal therapy with voriconazole and amphotericin B, she required penetrating keratoplasty for impending corneal perforation. Follow-up was uneventful, with no recurrence at 1 year. Fungal infections must be suspected in all corneal ulcers of traumatic etiology. Specific cultures and confocal microscopy must be performed early, so as to enable early treatment modification.

[Calculations of mean refraction and variation of refraction using a dioptric space]. / Réfraction moyenne et variation de réfraction calculées dans un espace dioptrique.

Polar notations (sphere, cylinder, and axis) of refraction perfectly characterize a single refraction but are not suitable for statistical analysis or graphic representation. While the spherical component of refraction can be easily analyzed by the spherical equivalent, statistical analysis of astigmatism requires non-polar expressions of refraction. Indeed, the cylinder and axis of astigmatism are not independent data. In addition, axis is a directional data including a non-trigonometric cycle. Refraction can be written in a non-polar notation by three rectangular coordinates (x, y, z), which can also represent the spherocylinder by one point in a dioptric space. These three coordinates constitute three independent (orthogonal) variables that correspond to a sphere-equivalent component and a pair of Jackson cross-cylinder components, oriented at 0°/90° (WTR/ATR astigmatism) and 45°/135° (oblique astigmatism). Statistical analysis and graphical representation become less complicated when using rectangular coordinates of refraction. Rectangular coordinates of the mean refraction are obtained by average rectangular coordinates. Similarly, rectangular coordinates of refraction change are obtained by a single subtraction of rectangular coordinates between the final and initial refractions. After statistical analysis, the rectangular coordinates obtained can be converted into a polar form for a more easily understood result. Finally, non-polar notations including rectangular coordinates are useful for statistical and graphical analysis, which would be difficult with only conventional polar notations of refraction.

[Polar and non polar notations of refraction]. / Les différentes expressions <> et <> de la réfraction.

Refraction can be expressed by four polar notations which correspond to four different combinations of spherical or cylindrical lenses. Conventional expressions of refraction (plus and minus cylinder notation) are described by sphere, cylinder, and axis. In the plus cylinder notation, the axis visualizes the most powerful meridian. The axis usually corresponds to the bow tie axis in curvature maps. Plus cylinder notation is also valuable for all relaxing procedures (i.e., selective suture ablation, arcuate keratotomy, etc.). In the cross-cylinder notation, two orthogonal cylinders can describe (without the sphere component) the actual refraction of both the principal meridians. This notation must be made before performing the vertex calculation. Using an association of a Jackson cross-cylinder and a spherical equivalent, refraction can be broken down into two pure components: astigmatism and sphere. All polar notations of refraction may perfectly characterize a single refraction but are not suitable for statistical analysis, which requires nonpolar expression. After doubling the axis, a rectangular projection breaks down the Jackson cross-cylinder, which has a polar axis, into two Jackson cross-cylinders on the 0 degrees /90 degrees and 45 degrees /135 degrees axis. This procedure results in the loss of the directional nature of the data. Refraction can be written in a nonpolar notation by three rectangular coordinates (x,y,z), which can also represent the spherocylinder by one point in a dioptric space. These three independent (orthogonal) variables have a concrete optical significance: a spherical component, a direct/inverse (WTR/ATR) component, and an oblique component of the astigmatism. Finally, nonpolar notations are useful for statistical analysis and graphical representation of refraction.

[Ocular response analyzer: feasibility study and correlation with normal eyes]. / Ocular response analyzer : étude de fiabilité et de corrélation sur des yeux normaux.

INTRODUCTION: To evaluate the accuracy of ocular response analyzer (ORA) parameters (corneal hysteresis (CH), corneal resistance factor (CRF), and ocular tension (IOPcc and IOPg)) and the correlation with corneal biometry measured with the Orbscan topographer. MATERIAL: and methods: The Ocular Response Analyzer is a new instrument that measures ocular rigidity/elasticity (CH and CRF) and intraocular pressure (IOPcc), which is assumed to be independent of corneal pachymetry. We compared the results of the ORA in 100 eyes with normal slit lamp examination, except ametropia, with the results from corneal measurements obtained with the Orbscan. RESULTS: A high correlation and a low difference between the right and left eyes show the accuracy of measurements (rS=0.84, p<0.001 and 8.52%). The mean CH and CRF were 10.25+/-1.6 mmHg (range, 6.5-14.4) and 10.25+/-1.85 mmHg (range, 4.9-14.2), respectively with a Gaussian distribution in normal eyes. The relationship between CH and CRF was significant with corneal pachymetry but not with IOPcc (corneal corrected). CH and CRF were related, although to a lesser extent, with corneal diameter and astigmatism power, but not to keratometry, sex, age, or spherical equivalent. CONCLUSION: The mean and the distribution of biomechanical factors are similar to the values found in the literature but the relationship to pachymetry seems to be stronger (pachymetry and corneal diameter) than what has been reported in previous publications. The new IOP corrected for the cornea is independent of pachymetry but is not significantly different from Goldmann IOP or IOP measured with a standard noncontact tonometer.

[Advantages of the autorefractometer and the Orbscan for measuring pupil diameter]. / Intérêt de l'auto-réfractomètre et de l'Orbscan pour la mesure du diamètre pupillaire.

PURPOSE: We compared pupil size measurements obtained with the Orbscan and autorefractometer to the Colvard Infrared pupillometer in order to determine their respective clinical advantages. MATERIAL AND METHODS: We prospectively measured the pupil diameter in 94 eyes of 47 normal patients using the Colvard device, the Nikon NKR 8000 autorefractometer, and the Orbscan device. For each device, two successive measurements were taken to determine its reproducibility. We also studied the relationship with the contralateral eye (i.e., difference and correlation). The measurements obtained with the different devices in different light intensities were compared and studied using regression analysis. RESULTS: Pupil diameter measured using the Orbscan had the highest reproducibility (mean difference between the two successive measurements: 3.8% or 0.15mm) and showed the smallest difference between the two eyes (5.0% or 0.19mm) and the strongest correlation with the contralateral eye (r=0.93; p<0.001). Scotopic Colvard measurements and autorefractometer measurements with low light settings were not significantly different (5.86mm versus 5.86mm; p=0.48). Autorefractometer measurements with low light settings showed the strongest correlation with the scotopic Colvard measurements (r=0.84; p<0.001). The Orbscan measurements were less correlated with the scotopic or photopic Colvard measurements (r=0.73; p<0.001 and r=0.51; p=0.003, respectively). For the Colvard pupillometer, the correlation between photopic measurements and scotopic measurements was also poor (r=0.51; p<0.001). CONCLUSION: Pupil size measurements with the autorefractometer may be advantageous before refractive surgery. Measuring pupil size in photopic conditions, as with the Orbscan, cannot screen people with large pupils in mesopic conditions.

[Prevention of proliferative vitreoretinopathy using 5-FU heparin: clinical tolerance and efficacy]. / Evaluation clinique de 5FU-héparine dans la prévention de la prolifération vitréorétinienne.

PURPOSE: To study the safety and efficacy of adjuvant combination therapy using 5-fluorouracil and heparin for prevention of proliferative vitreoretinopathy (PVR) during vitrectomy for retinal detachment surgery. METHODS: Two consecutive groups of 30 eyes with a rhegmatogenous retinal detachment (grade C1 or more) were prospectively compared. In the study group, 5-FU and heparin were administrated in the intraoperative infusion. Clinical safety and the efficacy were regularly studied over 1 year. RESULTS: In the 5-FU heparin therapy group, keratitis was more frequently observed the 1st day after surgery (p = 0.005), but not after 1 week (p = 0.54). However, conjunctival hyperemia was more severe after 1 and 7 days (p = 0.04). In both groups, no differences were found concerning intraocular pressure, postoperative hemorrhage or inflammatory reaction (flare) of the anterior chamber and the aspect of the eyelids (p > or = 0.14). The number of reoperations resulting from PVR, after 1 month and 1 year, was not significantly different between the two groups (p > or = 0.3). The reattachment rate and visual acuity (BSCVA) were not statistically different after 1 year (p > or = 0.12). CONCLUSION: Adjuvant combination therapy using 5-FU and heparin seems to be safe. However, its efficacy needs to be demonstrated by larger studies including eyes presenting a lower grade of PVR (grade B).

[Ocular biometry using Orbscan]. / Biométrie oculaire par Orbscan.

Orbscan is a recent optical device that combines the Placido disk of the videokeratoscope and a scanning slit. The scanning slit measures the elevation of both the corneal surface (anterior and posterior) and the anterior iris-lens surface. Biometric measures of the anterior segment such as corneal thickness, anterior chamber depth, corneal diameter, and iridocorneal angle are obtained using spatial coordinates of various ocular surfaces. Orbscan is not only a corneal topograph but a versatile device capable of measuring the biometry of the anterior segment of the eye.

[Crystalline lens biometry using A-scan ultrasound and the Orbscan device]. / Etude biométrique du cristallin par échographie A et Orbscan.

PURPOSE: To analyze the lens biometry obtained by Orbscan and A-scan ultrasound in normal eyes. MATERIAL: and methods: The lens thickness obtained by A-scan ultrasound and the anterior curvature of the crystalline lens obtained by Orbscan were prospectively recorded in 280 normal eyes (including eyes with ametropia) of 140 patients (10-95 years of age). The correlation of lens biometry with the contralateral measure, patient age and sex, subjective refraction, and other ocular biometric parameters (anterior chamber depth, iridocorneal angle, corneal diameter, central pachymetry, pupil, corneal radii of curvature, and posterior segment length) was assessed. RESULTS: The lens anterior curvature showed no significant correlation in particular with the subjective spherical equivalent; however, the quality of this measure was poor: the reproducibility of the lens anterior curvature was low (the average difference between two successive Orbscan measurements was 14.4%). The correlation with the contralateral eye was poor (rs=0.55; p<0.001 versus rs=0.97; p<0.001 for lens thickness). Lens thickness showed the strongest correlation with the patient's age (rs=0.82; p<0.001); it increased by 0.26 mm per decade. Lens thickness correlated with anterior chamber depth (rs=-0.72; p<0.001) and iridocorneal angle (rs=-0.65; p<0.001). The last two parameters also correlated with age (rs=-0.68; p<0.001 and rs=-0.62; p<0.001, respectively). Anterior chamber depth and iridocorneal angle decreased by -0.21 mm and -1.7 degrees , respectively, per decade. CONCLUSION: Lens thickness is mainly influenced by age and correlates with the anterior chamber depth and the iridocorneal angle. The influence of aging on anterior segment biometry essentially consists in an increase in lens volume.

[Pharmacological adjuvants for surgical treatment of proliferative vitreoretinopathy]. / Adjuvants pharmacologiques du traitement chirurgical de la prolifération vitréorétinienne.

Proliferative vitreoretinopathy (PVR) is the major cause of retinal detachment surgery failure. Many adjuvants were studied in vitro and on animals, some were studied on humans. Daunomycin seems to reduce PVR recidivism. 5-FU and steroids are nontoxic but their efficacy is not clear. Heparin reduced postoperative inflammation and seems to reduce PVR recidivism when associated with 5-FU. Associating heparin and steroids seems to reduce PVR in some groups of patients (aphakic, anterior PVR). Colchicine and retinoic acid per os are ineffective, silicone oil is effective as an internal tamponade but not as an adjuvant of PVR. Currently, no molecule has proven efficacy as an adjunctive treatment of PVR.

[Anterior segment of the eye and diabetes mellitus]. / Le segment antérieur de l'oeil des diabétiques.

OBJECTIVE: To study the damage to the anterior segment of the eye during mellitus diabetes. METHODS: We prospectively studied the anterior segment of the eye in 200 diabetic patients and 200 patients with no history of diabetes (control group). Parameters included the corneal curvature radius, corneal thickness, central corneal sensitivity (Cochet Bonnet esthesiometer), pupil diameter before and after dilation using tropicamide and phenylephrine eye drops, delay for maximal pupil dilation, lens transparency, and intraocular pressure. The damage to the anterior segment was compared in both groups and was correlated with the parameters of diabetes (type, duration, and equilibration), retinopathy grade, and peripheral neuropathy. RESULTS: Corneal geometry (i.e., curvature radius and thickness) and intraocular pressure did not correlate with diabetes. Cataract was significantly influenced by diabetes (p<0.001). The duration needed to obtain pharmacological maximal mydriasis significantly correlated with iris color (rs=0.47, p<0.001), patient age (rs=0.28, p<0.001) and diabetes (rs=0.25, p<0.001). Dilation was significantly longer in the diabetic patient than in those of the control group (36.5 min vs 30.7 min, p<0.001). Corneal sensitivity significantly correlated with age (rs=0.48, p<0.001) and diabetes (rs=0.53, p<0.001). Corneal sensitivity was decreased in the diabetic group (5.42 vs 5.94, p<0.001) and it correlated with retinopathy grade (rs=0.47, p<0.001) and with peripheral neuropathy (rs=0.15, p<0.001). Sensitivity and specificity of hypoesthesia in detecting peripheral neuropathy were 67.4% and 49.4%, respectively. Among the parameters of diabetes, duration of progression showed the strongest correlation with damage to anterior segment (rs > or = 0.25, p<0.001). CONCLUSION: Diabetes influences lens transparency, pharmacological pupil dilatation and corneal sensitivity. In spite of the unspecific character of the damage and the subjectivity of the measurement, corneal sensitivity is an interesting parameter to take into consideration among diabetic patients.

[The relationship between keratoconus and axial myopia]. / Relation entre le kératocône et la myopie axile.

PURPOSE: To study the relationship between keratoconus and axial myopia. METHODS: We prospectively studied refraction and ocular biometry in 100 consecutive keratoconus eyes, and 100 emmetropic eyes. Biometric data (including posterior segment length) were obtained by A-scan ultrasound, Orbscan, and ultrasonic pachymetry. Biometric measurements were compared in both groups. RESULTS: Anterior chamber depth, posterior segment length and axial length were significantly different between the two groups (p<0.001). Axial length was significantly greater in the keratoconus group than in the emmetropic group (23.97 mm versus 23.21 mm, p<0.001). Posterior segment length was significantly greater in the keratoconus group than in the emmetropic group (16.54 mm versus 15.99 mm, p<0.001). In the keratoconus group, the posterior segment length and the subjective spherical equivalent were significantly correlated (rs=-0.45, p<0.001). CONCLUSION: The increase in posterior segment length in the keratoconus group and the correlation between posterior segment length and spherical equivalent in the keratoconus group suggest a statistical relationship between keratoconus and axial myopia.

[Biometric study of acute-angle-closure glaucoma using Orbscan and echography]. / Analyse biométrique par Orbscan et échographie du glaucome aigu par fermeture de l'angle.

PURPOSE: To study acute-angle-closure glaucoma (AACG) biometry using Orbscan and echography. MATERIAL AND METHODS: We prospectively studied 200 normal eyes of 100 patients (including eyes with ametropia), 50 eyes of 25 patients before peripherial YAG laser iridotomy, 25 phakic eyes of 25 patients with a history of acute-angle-closure glaucoma (AACG) in the fellow eye. Both plane and polynomial modes of reconstruction of the iridocorneal angle measurement were analyzed. Biometric measurements of the three groups were compared. Biometric measurements (i.e., iridocorneal angle, anterior chamber depth, axial length, and lens thickness) and subjective spherical equivalent were correlated with the etiological classification. RESULTS: Age, sex, iridocorneal angle, anterior chamber depth, lens thickness, axial length and subjective spherical equivalent were significantly different in the three groups (p<0.002). The polynomial iridocorneal angle measurement was 43.4 degrees in the normal group, 36.5 degrees in the iridotomy group, and 28.4 degrees in the AACG group (p<0.001). Iridocorneal angle measurement correlated with the other biometric measurements (rs>0.51; p<0.001) and with the etiological classification (rs< or =0.68; p<0.001). The anterior chamber depth measurement obtained by Orbscan or echography was the best parameter for predicting ACCG (rs=0.77; p<0.001). CONCLUSION: The anterior chamber depth and polynimial iridocorneal angle obtained using the Orbscan device appears to be useful in predicting acute-angle-closure glaucoma.

Tissue crossmatch before corneal transplantation.

AIM: To investigate the influence of anticorneal antibodies on the outcome of transplantation in recipients before penetrating keratoplasty. METHODS: 100 consecutive penetrating keratoplasties performed between July 1995 and June 1996 were included in this study. Donor corneoscleral rim cryosections were incubated with recipient serum. Fixation of recipient IgM on donor corneas was revealed with a polyclonal anti-human mu-chain antibody. The mean follow up time was 61 months. Five years after transplantation, 63% of patients were available for follow up. During the follow up period, 15% of keratoplasties failed because of irreversible rejection. RESULTS: Anti-donor stromal lamellae IgM were found in 14 recipients. Anti-donor keratocyte IgM were present in 28 recipients. Dilution of recipient serum (up to 1/800) did not modify the results of positive crossmatch assays. Crossmatch assays performed with positive recipient sera and negative donor corneoscleral rims were negative. No significant influence of IgM crossmatch results on graft survival and rejection-free graft survival was found. CONCLUSION: Donor specific anticorneal stroma IgM were found in 28% of recipients before transplantation. This pre-immunisation was not associated with a higher risk of transplantation rejection.

[A study of pupil dilation using the Mydriasert ophthalmic insert]. / Etude de la dilatation pupillaire par l'insert ophtalmique Mydriasert.

PURPOSE: To evaluate the tolerance and efficiency of the Mydriasert(R) ophthalmic insert on pupil dilation. METHOD: Two pharmaceutical forms of a combination of tropicamide and phenylephrine (HCl) were compared on both eyes of 80 patients. For each patient, one Mydriasert insert (Ioltech) was placed in the lower conjunctival sac of the eye. Dilation of the control eye was obtained using 0.5% tropicamide eye drops and 10% phenylephrine eye drops (Novartis Ophthalmics), which were instilled with three frequency regimens (5, 10 or 15 min). The pupil diameter was regularly measured until the maximal mydriasis had occurred. RESULTS: Both subjective and objective tolerance of the insert was excellent. The size of the maximal mydriasis obtained when using the insert was significantly greater than that obtained when using the eye drops, regardless of the frequency of the instillation (p < 0.04). The difference in maximal pupil diameter ranged from +0.16 mm to +0.38 mm. Mydriasis kinetics was slower with the insert. The time necessary to obtain a maximal mydriasis was 47.3 min when the insert was used, whereas it was in the range of 31.4 to 38.5 minutes with the eye drops (p < 0.001). As far as pupil diameter is concerned, the superiority of the insert compared to the eye drops became observable only about 45 min after the insert had been placed in the eye. The relative efficacy of the insert compared to the eye drops did not correlate with patient features (p > or = 0.06). CONCLUSION: Despite the small quantity of drug delivered by the insert, Mydriasert allows a much greater mydriasis compared to that usually obtained when the eye drops were used. However, a longer time lapse is necessary for this to occur.

[Treatment of the sequelae of ocular burns using limbal transplantation]. / Traitement des séquelles de brûlures oculaires par la greffe de limbe.

PURPOSE: To report the results of limbal transplantation in patients with severe ocular burns and limbal stem cell deficiency. PATIENTS AND METHODS: This series includes six autografts (unilateral ocular burns) and five allografts (bilateral ocular burns) performed in ten eyes of ten males with an average age of 43 years. The origin of the ocular burn was chemical in eight cases and thermal in the remaining two cases. The average time between the initial trauma and limbal transplantation was 79 months. The average size of limbal grafts was 190 degrees (range: 80-20 degrees for autografts and 120-360 degrees for allografts). Patients with allografts received oral cyclosporine in three cases, topical cyclosporine in one case, and intravenous methylprednisolone in one case. Eight patients underwent penetrating keratoplasty an average of 11 months after limbal transplantation (range: 5-24 months). RESULTS: The average follow-up time was 36 months (range: 7-77 months). The overall success rate of limbal transplantation (ocular surface improvement) was 73% (8/11). The success rate of penetrating keratoplasty was 63% (5/8). The average initial visual acuity was 0.4/10 and the average final visual acuity was 1.6/10. Visual acuity improved by two lines or more in seven cases. DISCUSSION: Limbal transplantation is a useful surgical technique in patients with severe ocular burns. However, results remain insufficient and new techniques such as limbal stem cell culture and transplantation are needed to improve the visual prognosis of these patients.

[Incidence and factors influencing glaucoma after penetrating keratoplasty]. / Incidence et facteurs de risque de l'hypertonie oculaire au cours des kératoplasties transfixiantes.

PURPOSE: To determine the incidence and factors influencing glaucoma following penetrating keratoplasty. MATERIAL AND METHOD: We prospectively studied 440 consecutive patients undergoing penetrating keratoplasty over a period of 5 years, with an average follow-up of 2 years. High intraocular pressure was defined as IOP over 20 mmHg measured by Goldmann applanation for at least 1 week or if a patient required topical treatment for at least 1 week. Before surgery, 18.7% of the patients presented with glaucoma or high intraocular pressure; 44.9% received a graft for a bullous keratopathy condition, 25.6% had keratoconus, 31.5% received an anterior chamber lens, and 48.5% were phakic. RESULTS: After surgery, 42.2% of the patients had ocular pressure at 20 mmHg or more and required treatment for high ocular pressure. The increase in intraocular pressure appeared after an average delay of 3.3 +/- 4.7 months. The frequency of the increase in intraocular pressure was 54.3% for the bullous keratopathy patients, 26.6% for the keratoconus patients (p<0.001). At the end of the second year, the graft survival was 82.1% in absence of glaucoma, whereas it was 71.5% in cases of glaucoma after keratoplasty. Between all parameters that we studied, high intraocular pressure before surgery, etiology, the status, and receiver age over 60 years were the main factors influencing high intraocular pressure after keratoplasty. Intraocular pressure was correlated with the decrease in endothelial cell density and was at the origin of graft failure. Intraocular pressure correlated with the Best Spectacle Corrected Visual Acuity (BSCVA) by its effect on endothelial cell density and optic nerve destruction. CONCLUSION: The increase in intraocular pressure is a real and serious complication of keratoplasty. Its physiopathology is very complex. Better knowledge of risk factors can be useful in controlling it.

[Calculating the mean visual acuity and the change in visual acuity with a decimal acuity chart]. / Calculs de l'acuité visuelle moyenne et de la variation d'acuité visuelle à partir d'une échelle décimale.

The decimal visual acuity chart is not easy to use for statistical analysis and requires a transformation into LogMAR units (decimal logarithm of the Minimum Angle Resolution). In contrast to the decimal chart, the logarithmic chart has an arithmetic progression and a constant interval between lines. The LogMAR chart makes statistical analysis of visual acuity easy. Change in visual acuity is calculated directly by subtracting LogMAR data, while the average visual acuity is obtained with the arithmetic mean value of the LogMAR data. The mean acuity expressed in LogMAR units can be transformed into a decimal chart for a more comprehensive result. To calculate the average visual acuity directly from the decimal data, the geometric mean value must be used instead of the arithmetic mean value.