Optic Nerve Head Photographs Research Articles

Glaucoma diagnostics

Glaucoma diagnostics

Measuring Hemoglobin Levels in the Optic Nerve Head: Comparisons with Other Structural and Functional Parameters of Glaucoma

We evaluated and compared the ability of a new method for measuring hemoglobin (Hb) levels at the optic nerve head (ONH) to that of visual field evaluation, scanning laser ophthalmoscopy (HRT), scanning laser polarimetry (GDx), and optical coherence tomography (OCT) for diagnosing glaucoma. Healthy eyes (n = 102) and glaucomatous eyes (n = 101) underwent reliable Oculus Spark perimetry, and imaging with the HRT, GDx, and Cirrus OCT. In addition, ONH color images were acquired with a non-mydriatic fundus camera. The Laguna ON(h)E program then was used to calculate the Hb amount in each of 24 sectors of the ONH. Sensitivities at 95% fixed specificity, diagnostic agreement, and linear correlations between parameters with the best diagnostic ability were calculated. The glaucoma discriminant function (GDF) of the Laguna program, evaluating Hb in the vertical intermediate sectors and center/periphery Hb amount slope, yielded an 89.1% sensitivity and 95.1% specificity, which was superior or similar to the other tests. The best GDF diagnostic agreement was for the OCT-vertical cup-to-disc (C/D) ratio (kappa = 0.772) and the final phase Spark pattern SD (kappa = 0.672). Hb levels correlated strongly with the Spark mean sensitivity (first phase 0.70, final phase 0.71). Hb also correlated well with the Reinhard OW Burk discriminant function of the HRT (0.56), nerve fiber indicator of GDx (-0.64), and vertical C/D ratio of OCT (0.71). Hb levels evaluated by color analysis of ONH photographs had high reproducibility, a high sensitivity-specificity balance, and moderate to strong agreement with other structural and functional tests.

The Effect of Education on the Assessment of Optic Nerve Head Photographs for the Glaucoma Diagnosis

BackgroundTo evaluate the effect of one lesson of continuing medical education (CME) of subjective assessment of optic nerve head appearance on sensitivity and specificity for the diagnosis of glaucoma.MethodsOphthalmologists and residents in ophthalmology attending an international glaucoma meeting arranged at Malmö University Hospital, Malmö, Sweden, were asked to grade optic nerve head (ONH) photographs of healthy and glaucomatous subjects at two sessions separated by a lecture on glaucoma diagnosis by ONH assessment. Each grader had access to an individual portfolio of 50 ONH photographs randomly selected from a web-based data bank including ONH photographs of 73 glaucoma patients and 123 healthy subjects. The individual portfolio of photographs was graded before and after the lecture, but in different randomized order.ResultsNinety-six doctors, 91% of all attending the meeting, completed both assessment sessions. The number of correct classifications increased from 69 to 72% on the average. Diagnostic sensitivity increased significantly (p < 0.0001) from 70% to 80%, and the number of photographs classified as uncertain decreased significantly (p < 0.0001) from 22% to 13%. Specificity remained at 68%, and intra-grader agreement decreased.ConclusionCME had only a small effect on the assessment of ONH for the glaucoma diagnosis. Sensitivity increased and the amount of uncertain classifications decreased, while specificity was unchanged.

Automated volumetric evaluation of stereoscopic disc photography

PURPOSE: To develop a fully automated algorithm (AP) to perform a volumetric measure of the optic disc using conventional stereoscopic optic nerve head (ONH) photographs, and to compare algorithm-produced parameters with manual photogrammetry (MP), scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) measurements. METHODS: One hundred twenty-two stereoscopic optic disc photographs (61 subjects) were analyzed. Disc area, rim area, cup area, cup/disc area ratio, vertical cup/disc ratio, rim volume and cup volume were automatically computed by the algorithm. Latent variable measurement error models were used to assess measurement reproducibility for the four techniques. RESULTS: AP had better reproducibility for disc area and cup volume and worse reproducibility for cup/disc area ratio and vertical cup/disc ratio, when the measurements were compared to the MP, SLO and OCT methods. CONCLUSION: AP provides a useful technique for an objective quantitative assessment of 3D ONH structures.

The role of optical coherence tomography in the detection of pituitary adenoma

To analyse retinal nerve fibre layer (RNFL) thickness in eyes with compression of the optic chiasm by a pituitary adenoma. RNFL thickness was analysed with optical coherence tomography (OCT) and compared to visual field measurements using high-pass resolution perimetry (HRP). Sixteen eyes from eight patients with pituitary adenoma were studied. All had bitemporal visual field depression caused by compression of the optic chiasm. Patients were submitted to an ophthalmic examination more than 14 months after surgery (seven patients had undergone trans-sphenoidal and one trans-cranial adenomectomy). The examination included HRP, fundus photography and measurement of the peripapillar RNFL thickness using OCT. In spite of temporal visual field depression, not all eyes showed reduced RNFL thickness by OCT. This was also true for some eyes in which RNFL was judged to be reduced on fundus photographs. Contrary to our expectations, RNFL thickness in the nasal quadrant was normal in nine of the 16 eyes. Corresponding figures for the superior, inferior and temporal quadrants were eight, six and five, respectively. The overall RNFL thickness, as measured by OCT, did not correlate well with neural capacity, which is an index of remaining retino-cortical neural channels in HRP. RNFL thickness as measured with OCT was reduced in most, but not all, eyes with temporal field depression caused by chiasmal compression. The pattern of RNFL loss did not correlate well with the visual field defect. Sensitivity of RNFL thickness measurement in OCT was low. The method has limited value in the diagnosis of pituitary tumour compression.

The sensitivity and specificity of Heidelberg Retina Tomograph parameters to glaucomatous progression in disc photographs

Aim:To determine the sensitivity and specificity of the stereometric optic nerve head (ONH) parameters of the Heidelberg Retina Tomograph (HRT) to detect an event of progression verified in serial stereoscopic...

Epidemiology of Refractive Errors in an Adult European Population: The Segovia Study

Purpose: To determine the prevalence of refractive errors in Segovia, Spain. Methods: A cohort of 569 subjects was randomly selected in a stratified manner according to gender and age in a cross-sectional, population-based epidemiologic study, the target population of which was urban residents aged 40 to 79 years. All participants underwent an ophthalmic examination that included measurement of visual acuity (VA) and refraction, tonometry, anterior segment biomicroscopy, funduscopy, optic nerve head photography, and visual field testing. Of those, 417 subjects were enrolled who met the inclusion criteria of a phakic right eye and VA over 20/40. The prevalence of spherical errors was assessed after calculating the spherical equivalent and defining myopia as -0.5 diopters (D) or less and hyperopia as 0.50 D or more. The prevalence of astigmatism over 0.50 D was evaluated in minus cylinder form. Results: The estimated prevalences (95 confidence interval) of myopia, hyperopia, and astigmatism, in the population were 25.4% (21.529.8) 43.6% (3948.4), and 53.5% (48.758.2), respectively. No significant gender difference was found in the prevalence of any refractive errors. The prevalence of myopia or the mean value did not change significantly with age. The mean hyperopia and the mean astigmatism (p < 0.01 for both) and the prevalence increased with increasing age (p < 0.01 for both). Anisometropia of 1 D or more was present in 12.3% (49/396 subjects). Conclusion: More than 60% of the Segovia population over 40 years of age has a refractive error, with 25.4% myopic and 43.6% hyperopic. Astigmatism is present in over half of the population and the types change with age. © 2009 Informa Healthcare USA, Inc.

Concordance of flicker comparison versus side-by-side comparison in glaucoma

Background Flicker comparison superimposes baseline photos of the optic nerve head to subsequent photos, alternating them at a high frequency rate to create the perception of motion showing glaucomatous structural changes over time. The primary purpose of this study was to determine the degree of concordance among examiners in judging glaucomatous progression between serial optic nerve head photos using digital image flicker comparison versus the traditional side-by-side photograph comparison method. The secondary purpose was to determine if flicker comparison was quicker than side-by-side comparison. Methods A total of 29 eyes were selected from patient records at Nittany Eye Associates. Fourteen eyes showed various degrees of glaucomatous structural change among photos, while the remaining 15 eyes had no glaucomatous structural change. Three masked optometrists experienced in glaucoma management graded whether the photos represented glaucomatous change or no change when viewing photos randomly assigned to side-by-side or flicker comparison. Results Among multiple graders, flicker comparison gave moderate agreement, whereas side-by-side analysis gave fair agreement. The difference in time between the 2 methods was not statistically significant. Conclusions Flicker comparison is a unique, easy to learn, and an accurate way to view serial optic nerve head photographs. More study is needed to determine if flicker comparison is a useful tool in the clinical management of structural glaucoma progression.

Epidemiology of Refractive Errors in an Adult European Population: The Segovia Study

ABSTRACTPurpose: To determine the prevalence of refractive errors in Segovia, Spain. Methods: A cohort of 569 subjects was randomly selected in a stratified manner according to gender and age in a cross-sectional, population-based epidemiologic study, the target population of which was urban residents aged 40 to 79 years. All participants underwent an ophthalmic examination that included measurement of visual acuity (VA) and refraction, tonometry, anterior segment biomicroscopy, funduscopy, optic nerve head photography, and visual field testing. Of those, 417 subjects were enrolled who met the inclusion criteria of a phakic right eye and VA over 20/40. The prevalence of spherical errors was assessed after calculating the spherical equivalent and defining myopia as −0.5 diopters (D) or less and hyperopia as +0.50 D or more. The prevalence of astigmatism over 0.50 D was evaluated in minus cylinder form. Results: The estimated prevalences (95% confidence interval) of myopia, hyperopia, and astigmatism, in the population were 25.4% (21.5–29.8%) 43.6% (39–48.4%), and 53.5% (48.7–58.2%), respectively. No significant gender difference was found in the prevalence of any refractive errors. The prevalence of myopia or the mean value did not change significantly with age. The mean hyperopia and the mean astigmatism (p < 0.01 for both) and the prevalence increased with increasing age (p < 0.01 for both). Anisometropia of 1 D or more was present in 12.3% (49/396 subjects). Conclusion: More than 60% of the Segovia population over 40 years of age has a refractive error, with 25.4% myopic and 43.6% hyperopic. Astigmatism is present in over half of the population and the types change with age.

Glaucoma Management in Patients With Osteo-odonto-keratoprosthesis (OOKP)

To report diagnostic modalities and treatment options for glaucoma in eyes with osteo-odonto keratoprosthesis (OOKP). Eyes that underwent OOKP were evaluated for glaucoma at the time of the first postoperative visit, then at 1 and 3 months after the procedure, and thereafter every 6 months. All eyes underwent stereo-biomicroscopic optic nerve head (ONH) assessment, kinetic (Goldmann perimetry) and automated static visual field testing, ONH photography, Heidelberg retina tomograph, scanning laser polarimetery (GDx), and optical coherence tomography. Treatment of glaucoma was also reviewed. Average follow-up period was 19.1 (range: 5 to 31) months. Of the 15 eyes that underwent OOKP, 5 eyes had preexisting glaucoma. None of the other 10 eyes developed glaucoma after OOKP. ONH photography and visual field testing were the most reliable methods to assess status of the disease, whereas Heidelberg retina tomograph and optical coherence tomography could be performed with reasonable reproducibility and quality; GDx imaging was poor. All patients with glaucoma were treated with oral acetazolamide 500 mg twice a day. Transscleral cyclophotocoagulation was performed in 3 eyes at stage 2 of OOKP surgery. Progression of glaucoma was noted in 2 eyes on the basis of optic disc photographs and automated perimetry. Visual field testing and optic disc assessment with optic disc photographs seem to be effective methods to monitor eyes with OOKP for glaucoma. Treatment strategies include oral medications to lower intraocular pressure and cyclophotocoagulation.

Predicting Progressive Glaucomatous Optic Neuropathy Using Baseline Standard Automated Perimetry Data

To test the hypothesis that specific locations and patterns of threshold findings within the visual field have predictive value for progressive glaucomatous optic neuropathy (pGON). Age-adjusted standard automated perimetry thresholds, along with other clinical variables gathered at the initial examination of 168 individuals with high-risk ocular hypertension or early glaucoma, were used as predictors in a classification tree model. The classification variable was a determination of pGON, based on longitudinally gathered stereo optic nerve head photographs. Only data for the worse eye of each individual were included. Data from 100 normal subjects were used to test the specificity of the models. Classification tree models suggest that patterns of baseline visual field findings are predictive of pGON with sensitivity 65% and specificity 87% on average. Average specificity when data from normal subjects were run on the models was 69%. Classification trees can be used to determine which visual field locations are most predictive of poorer prognosis for pGON. Spatial patterns within the visual field convey useable predictive information, in most cases when thresholds are still well within the classically defined normal range.

Glaucoma Risk and the Consumption of Fruits and Vegetables Among Older Women in the Study of Osteoporotic Fractures

To explore the association between the consumption of fruits and vegetables and the presence of glaucoma. Cross-sectional cohort study. In a sample of 1,155 women located in multiple centers in the United States, glaucoma specialists diagnosed glaucoma in at least one eye by assessing optic nerve head photographs and 76-point suprathreshold screening visual fields. Consumption of fruits and vegetables was assessed using the Block Food Frequency Questionnaire. The relationship between selected fruit and vegetable consumption and glaucoma was investigated using adjusted logistic regression models. Among 1,155 women, 95 (8.2%) were diagnosed with glaucoma. In adjusted analysis, the odds of glaucoma risk were decreased by 69% (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.11 to 0.91) in women who consumed at least one serving per month of green collards and kale compared with those who consumed fewer than one serving per month, by 64% (OR, 0.36; 95% CI, 0.17 to 0.77) in women who consumed more than two servings per week of carrots compared with those who consumed fewer than one serving per week, and by 47% (OR, 0.53; 95% CI, 0.29 to 0.97) in women who consumed at least one serving per week of canned or dried peaches compared with those who consumed fewer than one serving per month. A higher intake of certain fruits and vegetables may be associated with a decreased risk of glaucoma. More studies are needed to investigate this relationship.

Heritable Features of the Optic Disc: A Novel Twin Method for Determining Genetic Significance

Numerous genetic diseases and environmental stimuli affect optic nerve morphology. The purpose of this study was to identify the principal heritable components of visible optic nerve head structures in a population-based sample of twins. Fifteen optic nerve specialists viewed stereoscopic optic nerve head photographs (Stereo Viewer-II; Pentax Corp., Tokyo, Japan) from 50 randomly selected monozygotic or dizygotic twin pairs. Before viewing, each expert was questioned about which optic nerve head traits they believed were inherited. After viewing a standardized teaching set, the experts indicated which twin pairs they thought were monozygotic. Participants were then questioned about how their decisions were reached. A rank-ordered Rasch analysis was used to determine the relative weighting and value applied to specific optic nerve head traits. The proportion of twin pairs for which zygosity was correctly identified ranged from 74% to 90% (median, 82%) across the panel. Experts who correctly identified the zygosity in more than 85% of cases placed most weighting on shape and size of the optic disc and cup, whereas experts with the lowest scores placed greater weighting on the optic nerve head vasculature in reaching their decisions. In determining the genetic components of the optic nerve head, the results of this study suggest that the shape and size of the optic disc and cup are more heritable and should receive a greater priority for quantification than should vascular features.

3D vs 2D qualitative and semiquantitative evaluation of the glaucomatous optic disc atrophy using computer-assisted stereophotography

Real colour documentation of the optic nerve head (ONH) is one of the most important methods to identify the early progression of glaucomatous optic nerve damage. This study compares the qualitative and semiquantitative evaluation of ONH photographs, using a 3D time-multiplexing system and conventional 2D photography, visualised on a computer monitor. Stereophotographs of the ONH were converted by special software in a 3D file. The same images were shown in 2D and 3D to 22 subjects with different training grades (residents and ophthalmologists). The evaluation based on a standardised questionnaire, containing semiquantitative parameters of the ONH. A weighted score for quality of ONH assessment counted the correct answers of the observers to compare their evaluation in 2D to the one made in 3D. All of the observers achieved a significant better evaluation of the ONH with 3D than with 2D images. No significant differences were observed between both groups. Classification errors with respect to the 'gold standard' were lower for 3D measurements as compared with 2D measurements (P=0.007). No significant differences were observed between the gold standard and residents or ophthalmologists for the ONH size, but for the c/dratio the stereoscopic images lead to better results. This study showed a better evaluation of parameters associated with the glaucomatous ONH atrophy with 3D images compared with 2D, independent of the clinical training grade. The computer-based evaluation of the ONH atrophy by using a time-multiplexing system (shutter-glasses) may improve the diagnosis of glaucoma patients.

Assessment of change of optic nerve head cupping in pediatric glaucoma using the RetCam 120

To ascertain the interobserver agreement among various specialists when analyzing images of the optic nerve head taken with the RetCam 120 (Clarity Medical Systems, Inc., Pleasanton, CA) for assessing the progression of optic disk cupping in pediatric glaucoma. Five observers compared pairs of RetCam 120 two-dimensional photographs from 64 eyes to identify whether or not changes in the optic disk had occurred. Observers included a pediatric glaucoma specialist, pediatric neurophthalmologist, strabismologist, pediatric ophthalmic imaging specialist, and pediatric ophthalmology fellow. Each was masked to the patient identity and clinical course. For each patient, the observers reviewed the photographs taken prior to therapy and at a minimum of 6 months following initiation of therapy. Interobserver variability was calculated and analysis conducted to identify influential variables. Poor agreement was noted between the observers. No significant association was obtained between agreement level and variables affecting photographic quality: variability of contrast and illumination, exposure and magnification, image clarity, presence of fluorescein on the cornea, and pixelation of the image with poor resolution. Raters noted problems with these image variables in 75.6% of the observations. The Kappa statistic obtained was kappa = 0.29 with overall proportion of agreement of p = 0.69, suggesting a fair agreement but not a moderate agreement. Comparison of RetCam 120 pediatric optic nerve head photographs, when performed subjectively by observers with different perspectives, and in isolation from clinical information, may not be a reliable indicator of cupping change. In addition, variations in image contrast, luminance, color, and pixelation pose significant challenges to agreement between observers. Comparison of RetCam 120 images should not be considered the sole criterion for monitoring pediatric glaucoma.

Temps-multiplex stéréophotographie : évaluation qualitative et semi-quantitative en 2D et 3D de l’atrophie optique glaucomateuse

Real color documentation of the optic nerve head (ONH) is one of the most important methods in identifying early progression of glaucomatous optic nerve damage. This study qualitatively and semiquantitatively compared the evaluation of ONH photographs, using a 3D time-multiplexing system and conventional 2D photography, visualized on a computer monitor. Twelve 15 degrees sequential stereophotographs from the Erlangen Glaucoma Registry were scanned by a SprintScan 35 Plus Film scanner (Polaroid, Waltham, MA, USA) and converted by computer software (3D-PIX, NuVision, McNaughton Inc., Beaverton, OR, USA) in jps format (3D). The same ONH images were shown in 2D and 3D to 22 subjects: 12 residents and ten ophthalmologists and evaluated using a standardized questionnaire. We observed a significantly better evaluation with stereoscopic pictures for both qualitative parameters (cup depth, visibility of the retinal nerve fibers, and the thinnest location of the neuroretinal rim) and quantitative parameters (c/d ratio and size of the disc, depending on the training level: in 3D better evaluation by the residents, in 2D by the ophthalmologists). With 2D pictures, we found better evaluation of the B zone and the stage of atrophy. Other than the method used for the entire evaluation, there was no significant difference between the groups. For the parameters weighed for clinical importance, the score of correct answers was significantly better with stereoscopic pictures. This study showed a significantly better evaluation of glaucomatous ONH atrophy with 3D images than with 2D pictures, independently of the evaluators' clinical training level. The computer-based evaluation of ONH atrophy using a time-multiplexing system (shutter glasses) may improve the diagnosis of glaucoma patients.

Humphrey Matrix Frequency Doubling Technology Perimetry and Optical Coherence Tomography Measurement of the Retinal Nerve Fiber Layer Thickness in Both Normal and Ocular Hypertensive Subjects

The purpose of this study was to determine by means of the Humphrey Matrix frequency doubling technology (FDT) perimetry and the optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurement whether functional and/or structural differences exist between normal and ocular hypertensive (OHT) subjects. One eye of 60 consecutive normal individuals and 60 OHT subjects was enrolled in this prospective observational comparative case series study. All subjects were examined at either the Ophthalmology Clinic, University of Chieti-Pescara, Chieti, Italy or the Department of Ophthalmology, S. Maria della Misericordia Hospital, Udine, Italy. All subjects underwent a full ophthalmic examination, including visual acuity, slit-lamp biomicroscopy, central corneal thickness ultrasound pachymetry measurement, achromatic automated perimetry, Matrix FDT perimetry, stereoscopic optic nerve head photography, and OCT. Matrix FDT perimetry mean deviation (MD), pattern standard deviation, glaucoma hemifield test, and 12 OCT RNFL thickness parameters were examined. Student t test, Bonferroni correction for multiple comparisons and receiver operator characteristics curve areas (AUROCs) were used to find any discrimination function between healthy and OHT eyes. Sensitivities at 83% and 92% specificities were reported. The FDT MD scores ranged from -1.10 to +3.80 decibels (db) in normal individuals and from -4.75 to +3.20 db in OHT subjects. The comparison between the average MD in the 2 groups showed a statistically significant difference (P=0.024). OCT showed a statistically significant difference between the 2 groups when examining the ratio between the inferior and the superior mean RNFL thickness (P=0.004). For OCT, the parameter with the largest AUROC for discriminating between healthy and hypertensive eyes was the ratio between the mean inferior and superior RNFL thickness (AUROC=0.85, sensitivity=75% at specificity=83%, sensitivity=67% at specificity=92%). For Matrix FDT perimetry, the parameter with the largest AUROC was MD (AUROC=0.78, sensitivity=67% at specificity=83%, sensitivity=58% at specificity=92%). Our results suggest that OHT eyes having a normal achromatic automated perimetry and a normal clinical disc appearance cannot be differentiated from normal eyes using conventional OCT parameters. When analyzing the ratio between inferior and superior average RNFL thickness, however, a significant difference is evident between healthy and hypertensive eyes. Using Matrix FDT perimetry, a significant difference in MD seems to exist between these 2 groups of eyes. The AUROCs confirm that OCT Iavg/Savg and Matrix FDT MD show the greatest sensitivity and specificity among the examined OCT and Matrix FDT parameters.

Agreement in Assessing Cup-to-Disc Ratio Measurement Among Stereoscopic Optic Nerve Head Photographs, HRT II, and Stratus OCT

To compare the level of agreement between subjective and objective methods in estimating horizontal and vertical cup-to-disc ratios (HCDR and VCDR, respectively) to determine if objective techniques may be used as surrogates for subjective cup-to-disc (CDR) estimation. Fifty-one glaucoma patients and 49 control subjects underwent full ophthalmic examination, stereoscopic optic nerve head photographs (ONHPs), confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomography II [HRT II]), and optical coherence tomography (Stratus OCT). The intraclass correlation coefficient (ICC) and Bland Altman plots were used to assess the agreement across the three methods. Repeated measures analysis of variance (ANOVA), Tukey adjustment, and pairwise P values were used to compare the HCDR and VCDR estimates between three clinicians who reviewed photos, Stratus OCT, and HRT II. For the clinicians, the agreement in subjectively assessed HCDR and VCDR was substantial (ICC=0.84 and 0.85, respectively), and for all three methods, overall agreement was good (ICC=0.75 and 0.77 for the HCDR and VCDR, respectively). Stratus OCT provided the largest overall mean+/-SD HCDR (0.68+/-0.14) and VCDR (0.62+/-0.13). The smallest overall mean+/-SD HCDR was provided by ONHP (0.32+/-0.16), and the smallest overall mean+/-SD VCDR was provided by HRT II (0.26+/-0.20). Repeated measures ANOVA test demonstrated significant differences across the three methods for glaucomatous (P=0.0017 and 0.0016, HCDR and VCDR, respectively) and normal (P=0.0001 for both HCDR and VCDR) eyes. Tukey adjustment demonstrated specific statistical differences between pairs of methods. Although the overall agreement between various methods was good, the mean estimates were statistically different. Additional studies are needed to evaluate the sources of variability, their level of significance, and longitudinal agreement between various methods of the CDR estimation.

Diagnostische Möglichkeiten zur Früherkennung der Glaukomprogression

To monitor the efficiency of glaucoma therapy it is necessary to detect progression of the disease as soon as possible. This survey presents the results on functional and morphological approaches to detect glaucoma progression. Risk factors identified in the therapeutic intervention studies should be used to evaluate the possible risk for progression. The functional test approaches of standard achromatic perimetry (SAP), short wavelength automated perimetry (SWAP) and frequency doubling technology (FDT) are described. Furthermore, morphologic changes are described by means of optic nerve head and nerve fiber photography, optic nerve head tomography, optic coherence tomography and nerve fiber polarimetry. The risk factors identified in the interventional studies were as follows: 1. higher intraocular pressure, 2. worse mean deviation (MD), 3. older age, and 4. frequent disc hemorrhages. Additionally, in patients with normal pressure glaucoma, migraine headaches were identified. Patients with ocular hypertension showed a higher risk of conversion into open angle glaucoma in case of higher pattern standard deviation (PSD), thinner central corneal thickness and larger vertical cup-to-disc ratio. The optic nerve head photography was the standard procedure of morphological monitoring in the interventional studies. A direct comparison of the available techniques on nerve fiber thickness and optic nerve head morphology is not yet available. SAP represents the functional methodology with the most validated results. SWAP and FDT showed that progression in early glaucoma can be detected before SAP damage occurs. Glaucoma patients should be regularly tested with SAP and optic nerve head photography. Automated nerve fiber or optic nerve head morphology measuring techniques might be favourable to complete the diagnostic monitoring. In patients without glaucomatous damage SWAP and FDT may be able to detect changes earlier than SAP. The results of a review of the literature are presented and discussed for each technology.

Digitizing Stereoscopic Optic Nerve Head Photographs for Storage and Viewing Using a Personal Computer

Careful examination and monitoring of optic nerve head changes is essential in the treatment of patients with glaucoma. This often results in accumulation of numerous photographs and required appropriate storage space. A simple, inexpensive, and efficient means of storing and viewing stereoscopic optic nerve head photographs is described. Images were acquired with a fundus camera, on a color slide film. Slides were then scanned and digitized. A handheld stereoscope was used for stereoscopic viewing on a computer monitor. A scanning resolution of 300 dpi appeared optimal. At this resolution, the storage utilization was 16 kilobytes and the scanning time was 160 seconds per patient.