High tech in the diagnosis of glaucoma

Scanning laser tomography (HRT, HRT II), scanning laser polarimetry (GDx nerve fibre analyser, GDx VCC), retinal thickness analyser (RTA) and optical coherence tomography (OCT, stratus OCT) provide objective measurements of the optic disc and the retinal nerve fibre layer suitable for the follow-up of glaucoma patients. Their ability to diagnose early glaucomatous damage is still limited but promising technical advances in this field can be expected in the future. For the moment, clinical examination and fundus photography still remain the gold standard for the assessment of glaucomatous optic disc and retinal nerve fibre layer damage.     

Application of retinal nerves fiber layer examination--GDx in patients with multiple sclerosis

PURPOSE: The purpose of our study is to evaluate retinal fiber layer thickness with scanning polarymetry laser (GDx), in patients suffering from SM with or without optic nerve symptoms. Multiple sclerosis proceeds to neurodegenerative changes and commonly appears with retrobulbar optic nerve damage. Examination of retinal nerves fiber layer examination with scanning laser polarymetry (GDx) enables to perform quantitative evaluation of retinal nerves fiber layer thickness within the area around the optic nerve disc. It finds application in diagnosis and monitoring of glaucoma, however its usefulness as a tool evaluating optic nerve in multiple sclerosis, has not been proved yet. MATERIALS AND METHODS: Subjects diagnosed with multiple sclerosis (SM) were divided into 2 groups. First group was comprised of subjects, who suffered from at least one episode of retrobulbar neuritis, in at least one eye. Second group was made up of 8 subjects with no history of retrobulbar neuritis. Retinal nerves fiber layer thickness was measured with scanning polarymetry laser (GDx). RESULTS: Symptoms of retinal nerves fiber layer damage, were discovered with GDx significantly more common in first group (70% vs 18.75% accordingly). CONCLUSIONS: Moreover, we stated that evaluation with scanning polarymetry laser might be precious method in discovering retinal nerves fiber layer damage in the course of multiple sclerosis. Presence of defects in retinal nerves fiber layer in patients suffering from multiple sclerosis with no history of retrobulbar neuritis may suggest subclinical damage of optic nerve.     

Scanning laser polarimetry in glaucoma

Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.     

Relation between size of optic disc and thickness of retinal nerve fibre layer in normal subjects

AIMS—To evaluate the relation between the optic disc size and the thickness of the peripapillary retinal nerve fibre layer (RNFL) in normal Japanese subjects by means of scanning laser polarimetry.
METHODS—Scanning laser polarimetry was performed in 60 normal subjects. One eye of each subject was randomly selected for study. Using a scanning laser polarimeter, the integral of RNFL thickness was measured totally and regionally within a circular band located 1.75 disc diameters from the centre of the optic disc. The correlation between the optic disc size and the integral of RNFL thickness was examined.
RESULTS—The optic disc size showed a significant correlation with the integral of RNFL thickness (R = 0.497, p <0.001). A significant negative correlation was observed between the optic disc size and the ratio of inferior integral to total integral of RNFL thickness (R = −0.274, p = 0.034).
CONCLUSIONS—The cross sectional area occupied by the RNF, measured by scanning laser polarimetry increased significantly with an increase in optic disc size while the ratio of inferior to total cross sectional area decreased significantly. These facts should be considered when one evaluates the RNFL thickness in patients with progressive optic neuropathies such as glaucoma.

Keywords: scanning laser polarimeter; normal subjects; optic disc; retinal nerve fibre layer     

The role of scanning laser polarimetry using the GDx variable corneal compensator in the management of glaucoma suspects

AIM: To determine the role of scanning laser polarimetry using the GDx variable corneal compensator (VCC) in the management of glaucoma suspects. METHODS: Over a 12-month period, 43 of 447 (9.6%) patients referred to a glaucoma screening clinic were classified as "glaucoma suspects" when it was not possible to categorise the optic disc appearance and visual fields as definitely glaucomatous or definitely normal. Of these patients, 39 underwent a full ophthalmic review, including assessment of the visual fields and analysis of the retinal nerve fibre layer with the GDx VCC. RESULTS: After the review, 17 of 39 (43.6%) patients were discharged because of normal GDx VCC results. The remaining 22 of 39 (56.4%) were considered to be at risk of developing progressive glaucoma, and further follow-up in the hospital eye service was recommended. 3 (7.7%) patients received treatment. Of the 22 patients, 12 were considered to have pre-perimetric normal tension glaucoma, 7 normal tension glaucoma and 1 primary open-angle glaucoma (POAG). In 19 of these patients, abnormal GDx VCC results were found, particularly inter-eye asymmetry in the nerve fibre layer thickness. However, in 2 of 39 (5.1%) patients the GDx VCC was normal, despite the presence of a neuroretinal rim defect in the optic disc with corresponding visual field loss, and in 1 patient with POAG. CONCLUSIONS: Scanning laser polarimetry using the GDx VCC is an important tool in defining the management strategies of glaucoma suspects. In screening for glaucoma, however, GDx VCC results should not be used in isolation, but in conjunction with conventional methods of optic disc and visual field assessment.     

Scanning laser polarimetry versus frequency-doubling perimetry and conventional threshold perimetry: changes during a 12-month follow-up in preperimetric glaucoma. A pilot study.

PURPOSE: To evaluate the possibility for detecting the progression in preperimetric primary open angle glaucoma (POAG) using scanning laser polarimetry (SLP), frequency-doubling technology (FDT), and conventional automated perimetry (AP). PATIENTS AND METHODS: 22 eyes of 11 preperimetric POAG patients were evaluated using SLP (Nerve Fiber Analyzer, GDx), AP (Humphrey 24-2 threshold test) and FDT (30 degrees threshold test). All eyes had intraocular pressure (IOP) higher than 21 mmHg before treatment, but were consistently lower than 22 mm Hg with unchanged topical medication before and during the study. At the initial evaluation session optic nerve heads showed mild glaucomatous changes but the visual fields were normal (MD better than 2.0 dB, Glaucoma Hemifield Test: within normal limits or borderline). AP and FDT measurements were repeated 6 months later, and all three tests were repeated 12 months after the first investigation. RESULTS: IOP, AP and FDT measurements showed no statistically significant changes during the 12-month follow up period. In contrast to this, a tendency for a glaucomatous type decrease was seen with SLP in the retinal nerve fibre layer (RNFL) thickness parameters (mean superior and inferior sector thickness values, ellipse average thickness and maximal modulation). The mean decrease of RNFL thickness in the superior and inferior sectors was 2.77 microm and 2.48 microm, respectively. Using the two-way nested ANOVA, which considers the relation between the right and left eyes of the subjects, the decrease was statistically significant (p=0.021) for the inferior sector RNFL thickness. CONCLUSION: The results suggest that scanning laser polarimetry is a useful technique to detect and measure glaucomatous progression in early glaucoma. Scanning laser polarimetry of the RNFL may help to detect and quantify early progression even if worsening is not seen with perimetry and FDT tests.     

Scanning laser polarimetry of the retinal nerve fiber layer in central retinal artery occlusion

PURPOSE: To report the results of scanning laser polarimetry (NFA/GDx; Laser Diagnostic Technologies, San Diego, CA). DESIGN: Prospective, consecutive observational case series. PARTICIPANTS: Ten consecutive patients with central retinal artery occlusion (CRAO). METHODS: Neuro-ophthalmic examination and scanning laser polarimetry of the retinal nerve fiber layer (RNFL) of 10 patients with CRAO. MAIN OUTCOME MEASURES: Duration of visual loss, visual acuity, funduscopy, and scanning laser polarimetry of the RNFL in 10 eyes of 10 patients with CRAO. RESULTS: The duration of visual loss before examination and scanning laser polarimetry ranged from 1 to 7 days. Visual acuity was counting fingers at 1 foot or worse in all 10 eyes with CRAO, and funduscopy revealed pallid retinal edema accompanied by a cherry red spot in all affected eyes. Funduscopy of the fellow eyes in all but one patient, who had anterior ischemic optic neuropathy and was subsequently diagnosed with giant cell arteritis, revealed no acute changes. Scanning laser polarimetry of all eyes with CRAO revealed diffuse attenuation of the retardation of the RNFL. Scanning laser polarimetry of the fellow eye revealed a normal bimodal distribution in the eight patients in whom it could be measured. In one patient who was examined 1 day after the onset of visual loss, repeat nerve fiber analysis 6 weeks later revealed further depression of the RNFL compared with the initial scan. Repeat analysis of the RNFL in four other patients showed persistence of the diffuse depression noted during their initial examinations. CONCLUSIONS: Scanning laser polarimetry in CRAO reveals diffuse depression of the retardation of the RNFL, which occurs acutely after the onset of visual loss. To our knowledge these patients represent the first reports of scanning laser polarimetry of the RNFL in acute CRAO.     

Laser scanning topography and polarimetry with implantation of intraocular lenses before and after cataract surgery]

BACKGROUND: In the last years, scanning laser measurements were established in glaucoma diagnostics. Techniques of special interest are scanning laser topometry (SLT) for exact measurements of the optic disc and its cup and scanning laser polarimetry (SLP) for precise assessment of the retinal nerve fiber layer thickness. As glaucoma patients often suffer from a cataract, too, and a trabeculectomy additionally favors the advance of lens opacities, in the follow up of glaucoma patients cataract surgery is often necessary. PATIENTS AND METHODS: The influence of cataract surgery in phacotechnique with intraocular lens implantation (31 PMMA-IOLs, Pharmacia/Upjohn, model 811 B, and 25 HEMA/MMA-IOLs, Technomed, Memory Lens) on SLT and SLP was evaluated before and 3 to 4 weeks after cataract surgery in 56 eyes of otherwise healthy patients. Lens opacities were classified according to LOCS III. For SLT, we applied a TopSS, and for SLP a Nerve Fiber Analyzer II and a GDx (LDT, USA). RESULTS: Our results show that SLT and SLP are mostly performable at lens opacities with visual acuity reductions down to 0.16. In SLT, we usually found no big differences in the assessed parameters before and after cataract surgeries with IOL implantation. Standard deviations between three single measurements were mostly smaller postop. In SLP, nerve fiber layer patterns were very similar before and after cataract surgeries with IOL implantation whereas total nerve fiber layer thickness values postoperatively were slightly higher. CONCLUSIONS: Our results indicate that cataract surgeries with IOL-implantation have only mild influence on SLT and SLP. These findings seem to be of clinical interest especially in the follow up of glaucoma patients.     

Strukturelle Diagnostik der Verlaufsbeobachtung der Glaukome

Background

Imaging of the structural progression of glaucoma enables measurement of the neuroretinal rim of the optic disc, retinal nerve fibre layer and thickness of the ganglion layer.

Methods

High resolution disc photography, laser scanning tomography, scanning laser polarimetry and optical coherence tomography (OCT) are the current methods of choice to document and measure progression of this chronic degenerative disease.

Results

Loss of the neuroretinal rim is only a few mm² or mm³ per year and has to be differentiated from age-related loss which shows less change over the years. The most pronounced loss is temporal both superior and inferior. Thinning of the retinal nerve fibre layer follows the same pattern with significant annual changes of only 6–7 µm. Modern OCT devices deliver measurements of the macula ganglion cell complex which can be even more sensitive than the thickness of the retinal nerve fibre layer. Qualitative criteria for structural progression are papillary hemorrhage, rarification of papillary vessels and specific changes of the retinal pigment epithelium.

Conclusions

Structural loss due to glaucoma can be imaged and measured with different methods in different tissues. The evaluation of significant changes is still the responsibility of the ophthalmologist by taking all findings into account.     

Assessment of optic disc anatomy and nerve fiber layer thickness in ocular hypertensive subjects with normal short-wavelength automated perimetry

PURPOSE: To compare optic disc topography and nerve fiber layer thickness in ocular hypertensive eyes and normal subjects. DESIGN: Prospective, case-controlled study. PARTICIPANTS AND CONTROLS: One eye in each of 20 normal and 27 ocular hypertensive patients was enrolled. METHODS: Consecutive normal and ocular hypertensive patients were enrolled. Each patient underwent complete ophthalmic examination, achromatic automated perimetry, short-wavelength automated perimetry, confocal scanning laser ophthalmoscopy, confocal scanning laser polarimetry, and optical coherence tomography. The intraocular pressure was 21 mmHg or less for normal subjects and at least 25 mmHg on two separate occasions in ocular hypertensive eyes. Structural parameters were compared between the two groups. Eyes with evidence of glaucomatous optic neuropathy, achromatic visual field loss, or evidence of focal visual field injury during short-wavelength automated perimetry were excluded. MAIN OUTCOME MEASURES: Optic nerve head topography and nerve fiber layer thickness. RESULTS: The three imaging technologies could not detect differences in optic disc or nerve fiber layer anatomy between the two groups. Ocular hypertensive eyes had a greater corrected pattern standard deviation than normal eyes during short-wavelength automated perimetry (P = 0.04). CONCLUSIONS: Ocular hypertensive eyes with normal achromatic automated perimetry and short-wavelength automated perimetry could not be distinguished from normal subjects with confocal scanning laser ophthalmoscopy, confocal scanning laser polarimetry, and optical coherence tomography.     

Clinical value of scanning laser polarimetry in glaucoma diagnostics

The term glaucoma is used as a melting pot of many different diseases which have in common that the retinal ganglion cells and their axons are damaged. Untreated, apoptosis can be induced causing ganglion cell death which subsequently leads to typical glaucomatous damage at the optic nerve head, scotomas of the visual fields, and in the worst case scenario to blindness. It is well known that patients with glaucoma can suffer a 20 to 50?% loss of retinal ganglion cells before a defect becomes evident in standard white on white perimetry. To prevent glaucomatous damage, it is important to detect changes of the retinal ganglion cells and their nerve fibre layer as early as possible and to monitor their follow-up as closely as possible in order to find an adequate treatment of glaucoma, and to control its efficiency. In the past few years, scanning laser polarimetry by means of GDx technology (Carl Zeiss Meditec, Dublin, USA) could be established as a new method to measure the retinal nerve fibre layer not only qualitatively but even quantitatively. Presently, the GDx plays an important role in actual glaucoma diagnostics on account of its high resolution, the comfort for both patient and user, and its highly reproducible measurements. Especially in difficult evaluable optic nerve heads (e.?g., micro- and macrodiscs), tilted discs, and optic disc anomalies (e.?g., optic nerve drusen) modern nerve fibre diagnostics by means of GDx technology is a helpful enrichment in clinical routine.     

Alterations in retinal nerve fiber layer thickness following indirect traumatic optic neuropathy detected by nerve fiber analyzer,GDx-N

PURPOSE: To evaluate changes in the retinal nerve fiber layer following traumatic optic neuropathy. DESIGN: Observational case report. METHODS: A patient presented with visual loss after an accident. Scanning laser polarimetry was performed. RESULTS: Thickness of the retinal nerve fiber layer increased immediately after the trauma but then progressively decreased. Severe loss was observed at day 90 and then ceased. Enlargement of the optic disk cup was also observed. CONCLUSIONS: This is the first report documenting early transient increase followed by progressive loss of the retinal nerve fiber layer in traumatic optic neuropathy.     

Retinale Nervenfaser schichtdicke und peripapillärer Blutfluss bei Glaukompatienten und Gesunden

BACKGROUND: In progressive glaucoma there is increasing loss of retinal nerve fibers and therefore decreasing nerve fiber layer thickness. As measurements of capillary blood flow have been reported to depend on nerve fiber layer thickness, this could result in incorrectly high blood flow measurements in patients with advanced glaucoma. METHODS: In 33 healthy controls and 59 glaucoma patients we measured retinal nerve fiber layer thickness by laser polarimetry and relative capillary blood flow by scanning laser doppler flowmetry three times on the nasal and temporal peripapillary retina. For statistical analysis a regression analysis was used. RESULTS: The correlation coefficients for volume, velocity, and flow with nerve fiber layer thickness at the same location were 0.02/-0.03/-0.02 in the temporal retina and -0.22/-0.07/-0.19 in the nasal retina (all correlations nonsignificant). CONCLUSION: No correlation was found between nerve fiber layer thickness and capillary blood flow. Measurement of capillary blood flow in glaucoma patients thus does not appear to be affected by decreasing nerve fiber layer thickness.     

Evaluation of retinal nerve fiber layer thickness measurement following laser in situ keratomileusis using scanning laser polarimetry

AIM: To evaluate the effect of laser-assisted in situ keratomileusis (LASIK) on the measurement of retinal nerve fiber layer thickness by scanning laser polarimetry using customized corneal compensation in myopes. MATERIALS AND METHODS: Scanning laser polarimetry was performed on 54 eyes of 54 healthy patients with myopia using the glaucoma diagnostics variable corneal compensation (GDx VCC) instrument (Laser Diagnostic Technologies, San Diego, California) before and a week after LASIK. The various parameters were compared using the Student's t test. RESULTS: No statistically significant change was observed in any of the retinal nerve fiber layer parameters before and after LASIK. CONCLUSIONS: While the measurement of retinal nerve fiber layer thickness by scanning laser polarimetry is affected by anterior segment birefringent properties and LASIK would be expected to produce changes in the same, customized corneal compensation using the GDx VCC seems to adequately compensate for these changes.     

Optical coherence tomography and scanning laser polarimetry in normal, ocular hypertensive, and glaucomatous eyes

PURPOSE: To evaluate the relationship between visual function and retinal nerve fiber layer measurements obtained with scanning laser polarimetry and optical coherence tomography in a masked, prospective trial. METHODS: Consecutive normal, ocular hypertensive, and glaucomatous subjects who met inclusion and exclusion criteria were evaluated. Complete ophthalmologic examination, disk photography, scanning laser polarimetry, optical coherence tomography, and automated achromatic perimetry were performed. RESULTS: Seventy-eight eyes of 78 patients (17 normal, 23 ocular hypertensive, and 38 glaucomatous) were enrolled (mean age, 56.8+/-11.5 years; range, 26 to 75 years). Eyes with glaucoma had significantly greater neural network scores on scanning laser polarimetry and lower maximum modulation, ellipse modulation, and mean retinal nerve fiber layer thickness measured with optical coherence tomography compared with normal and ocular hypertensive eyes, respectively (all P<.005). Significant associations were observed between neural network number (r = -.51, r = .03), maximum modulation (r = .39, r = -.32), ellipse modulation (r = .36, r = -.28), and optical coherence tomography-generated retinal nerve fiber layer thickness (r = .68, r = -.59) and visual field mean deviation and corrected pattern standard deviation, respectively. All scanning laser polarimetry parameters were significantly associated with optical coherence tomography-generated retinal nerve fiber layer thickness. CONCLUSION: Optical coherence tomography and scanning laser polarimetry were capable of differentiating glaucomatous from nonglaucomatous populations in this cohort; however considerable measurement overlap was observed among normal, ocular hypertensive, and glaucomatous eyes. Retinal nerve fiber layer structural measurements demonstrated good correlation with visual function, and retinal nerve fiber layer thickness by optical coherence tomography correlated with retardation measurements by scanning laser polarimetry.     

The effect of myelination on perimetry and retinal nerve fibre analysis

Background: Myelinatecl retinal nerve fibres around the optic nerve head can lead to an enlargement of blind spot with kinetic perimetry. Presumably extensive myelination will also decrease the visual sensitivity with static perimetry. This study reports the effect of myelination on static perimetry in several patients. Scanning laser polarimetry can measure the retinal nerve fibre layer thickness around the optic nerve head in vivo. This technique was applied at the myelination to investigate its effect on retinal nerve fibre layer thickness determination. Methods: Four eyes of three subjects with myelination around the optic nerve head were tested with Bjerrum screen at one metre to measure the blind spot size. They were followed by Humphrey Visual Field Analyser with a custom pattern to quantify the threshold level at the blind spot region. A GDx Nerve Fiber Analyser was used to measure the retinal nerve fibre layer thickness around the optic nerve head. Results: All the patients demonstrated an enlargement of the blind spot, with different extents, corresponding to the area of myelination. Threshold testing revealed a depression in the myelinated regions. The results for retinal nerve fibre layer were not conclusive with two eyes demonstrating thickening and two eyes showing no effect from myelination. Conclusions: A static field test with a modern visual field analyser may help to quantify the effect of myelination on visual sensitivity. More studies on the effect of myelination on retinal nerve fibre layer thickness measurement are suggested with more subjects involved.     

Analysis of the Peripapillary Retinal Nerve Fibre Layer Thickness Using Optical Coherence Tomography in Traumatic Optic Neuropathy

The aim of the study is to evaluate the change in thickness of the retinal nerve fibre layer following acute traumatic optic neuropathy using optical coherence tomography. Twenty-eight patients who had unilateral decreased visual acuity and who were diagnosed with traumatic optic neuropathy were evaluated. Twelve eyes in the 28 patients who had trauma to the orbit or head resulting in traumatic optic neuropathy were serially examined every 2 weeks for 6 weeks and again at 12 and 24 weeks after the trauma. The progressive axonal change in retinal nerve fibre layer thickness was examined with disc optical coherence tomography. The mean age of the 12 patients was 48.58?±?21.64 years. The mean retinal nerve fibre layer thickness at the second week after trauma was 95.03?±?5.93 μm; this mean thickness decreased sequentially over the next 6 months and was 50.61?±?5.99 μm at 24 weeks after trauma. Retinal nerve fibre layer thickness decreased at a faster rate during the first 6 weeks after trauma than in any other period, and the rate of this decrease became stable 6 months after the trauma. The superior and inferior portions of the optic disc showed greater reductions in retinal nerve fibre layer thickness than other areas. The authors conclude that in cases of traumatic optic neuropathy, retinal nerve fibre layer thickness decreased sequentially for 6 months. Most of this decrease occurred during the first 6 weeks after trauma.     

Current imaging of the optic disk and retinal nerve fiber layer

The optic nerve head and the retinal nerve fiber layer (RNFL) are the sites of clinically detectable glaucomatous tissue damage. Photographic techniques are used to document the optic disk and the RNFL to monitor patients with suspected primary open-angle glaucoma or to follow-up patients already suffering from this disease. New techniques such as laser scanning tomography (LST), scanning laser polarimetry, and optical coherence tomography have been introduced to quantify structural alterations with the aim of early detection of optic nerve or RNFL damage prior to functional loss. These novel, additional diagnostic tools are currently being evaluated in clinical practice. While scanning laser polarimetry and optical coherence tomography are discussed elsewhere in this volume, articles on LST and conventional techniques are considered here. Imaging and computed data processing allow for three-dimensional in vivo measurements in the range of micrometers. With regard to the structure of the optic nerve head, this aspect in the evaluation of the optic disk can be based on quantitative topographic data. We expect "topometry" to become an important additional tool in the early diagnosis and follow-up of patients with glaucoma. However, computed parameter readings should always be evaluated in a clinical context. The goal is to improve, combine, and integrate all the different diagnostic approaches to improve patient care for the benefit of those suffering from glaucoma.     

New developments in scanning laser polarimetry for glaucoma

PURPOSE OF REVIEW: Scanning laser polarimetry is a technique that is used to evaluate the thickness of the retinal nerve fiber layer. It has been shown to have a high accuracy for diagnosing glaucoma. In a subset of eyes, atypical retardation patterns may be present that do not match the expected retinal nerve fiber layer appearance. This review summarizes recent advances made to reduce the frequency and severity of these patterns. In addition, recent progress in the development of algorithms for detecting progression is discussed. RECENT FINDINGS: A new measurement algorithm--enhanced corneal compensation--has been developed to improve the instrument's signal-to-noise ratio. Enhanced corneal compensation has been shown to improve the accuracy of scanning laser polarimetry for diagnosing glaucoma. In addition, enhanced corneal compensation improves the relationship between standard automated perimetry and scanning laser polarimetry measurements. Furthermore, research is being done on detecting progression in glaucoma. Recently, a method for simulating progression has been proposed, thereby diminishing the need for long-term studies to validate numerous measurement algorithms. SUMMARY: With enhanced corneal compensation, the diagnostic accuracy of scanning laser polarimetry has been further improved for glaucoma. Newly developed algorithms for detecting any progressive retinal nerve fiber layer thinning await clinical validation.     

Scanning laser polarimetry of the retinal nerve fibre layer in primary open angle and capsular glaucoma

AIMS—To evaluate the clinical value of scanning laser polarimetry with the nerve fibre analyser type II in primary open angle glaucoma (POAG) and capsular glaucoma.
METHODS—Scanning laser polarimetry was performed on one eye of 30 patients suffering from POAG, 25 patients suffering from capsular glaucoma, and on 35 healthy control subjects. The retinal nerve fibre layer (RNFL) thickness values were compared among the groups. Reproducibility of the measurements was calculated and the influence of pilocarpine induced miosis on the results was investigated.
RESULTS—RNFL thickness in the superior and inferior sectors, as well as along the total circumference was significantly lower in both glaucoma groups than in the control eyes (p<0.05). None of the thickness values differed between the two glaucoma groups. Reproducibility was comparable in all groups; the coefficient of variation varied between 3.0% and 8.9% for the different sectors investigated. Miosis had no significant impact either on the thickness values or on the reproducibility (p>0.05).
CONCLUSION—The results suggest that scanning laser polarimetry is a useful method for nerve fibre layer analysis in glaucoma, and that it is not influenced by the pupil size.