Retinal nerve fiber layer thickness in patients with exfoliation, exfoliative glaucoma, and primary open angle glaucoma

Evaluation of retina nerve fiber layer, ganglion cell-inner plexiform layer and lamina cribrosa in clinically unilateral exfoliative glaucoma

PURPOSE

To compare retinal nerve fiber layer (RNFL), ganglion cell-inner plexiform layer (GC-IPL), the lamina cribrosa depth (LCD) and thickness (LCT) in unilateral exfoliative glaucoma (EXG) patients with their fellow eyes without exfoliation and control eyes.

METHODS

This cross-sectional prospective single-center study consisted of 64 eyes of 32 patients with unilateral EXG and 35 eyes of controls. All subjects were examined with spectral domain optical coherence tomography for the RNFL and GC-IPL measurements. The LCD and LCT measurements were also obtained.

RESULTS

The RNFL measurements at all quadrants were statistically thinner in EXG eyes than those in their eyes without EXG and control eyes (p < 0.001 for average, superior, temporal and inferior; p = 0.004 for nasal). The EXG group had deeper LCD than their eyes without EXG and control eyes (p < 0.001, for both). The fellow eyes of EXG group had also deeper LCD than control eyes, with no statistical significance (p = 0.058). The mean LCT was thinner in EXG eyes compared to those in the eyes without EXG and control eyes (p < 0.001, for both). The eyes without EXG and control eyes had similar LCT (p = 0.293).

CONCLUSIONS

Recent developments in imaging technology give the clinician detailed structural information about optic nerve head and retina such as GC-IPL, LCD and LCT. In addition to follow-up of RNFL changes, these new parameters may be useful in recognizing progression in EXG patients.

Diurnal and 24-h Intraocular Pressures in Glaucoma: Monitoring Strategies and Impact on Prognosis and Treatment

The present review casts a critical eye on intraocular pressure (IOP) monitoring and its value in current and future glaucoma care. Crucially, IOP is not fixed, but varies considerably during the 24-h cycle and between one visit and another. Consequently, a single IOP measurement during so-called office hours is insufficient to characterize the real IOP pathology of a patient with glaucoma. To date IOP remains the principal and only modifiable risk factor for the development and progression of glaucoma. Only by evaluating IOP characteristics (mean, peak and fluctuation of IOP) at diagnosis and after IOP-lowering interventions can we appreciate the true efficacy of therapy. Unfortunately, a major limiting factor in glaucoma management is lack of robust IOP data collection. Treatment decisions, advancement of therapy and even surgery are often reached on the basis of limited IOP evidence. Clearly, there is much room to enhance our decision-making and to develop new algorithms for everyday practice. The precise way in which daytime IOP readings can be used as predictors of night-time or 24-h IOP characteristics remains to be determined. In practice it is important to identify those at-risk glaucoma patients for whom a complete 24-h curve is necessary and to distinguish them from those for whom a daytime curve consisting of three IOP measurements (at 10:00, 14:00 and 18:00) would suffice. By employing a staged approach in determining the amount of IOP evidence needed and the rigour required for our monitoring approach for the individual patient, our decisions will be based on more comprehensive data, while at the same time this will optimize use of resources. The patient’s clinical picture should be the main factor that determines which method of IOP monitoring is most appropriate. A diurnal or ideally a 24-h IOP curve will positively impact the management of glaucoma patients who show functional/anatomical progression, despite an apparently acceptable IOP in the clinic. The potential impact of nocturnal IOP elevation remains poorly investigated. The ideal solution in the future is the development of non-invasive methods for obtaining continuous, Goldmann equivalent IOP data on all patients prior to key treatment decisions. Moreover, an important area of future research is to establish the precise relationship between 24-h IOP characteristics and glaucoma progression.

Structural Changes in Pseudoexfoliation Syndrome Evaluated with Spectral Domain Optical Coherence Tomography

PURPOSE

To detect early structural changes of macular ganglion cell complex (GCC), peripapillary nerve fiber layer (pNFL), and optic nerve head (ONH) topography in subjects with pseudoexfoliation (PEX) using 3-D spectral domain optical coherence tomography (SD-OCT, Topcon 3D-2000).

MATERIALS AND METHODS

Thirty-five participants with PEX and 29 healthy control subjects were included in the study. All study participants underwent SD-OCT imaging. Macular NFL, ganglion cell layer and inner plexiform layer (GCL + IPL), pNFL, and ONH parameters were measured in each participant. The results were compared within the two groups.

RESULTS

In eyes with PEX, the superior and total mNFL thickness; superior, and total GCL + IPL thickness; superior, inferior, and total GCC thickness; and inferior, temporal, nasal, and total pNFL thickness were significantly thinner than the control subjects. In the topographic evaluation of ONH, there was no significant difference in optic disc area (ODA), cup area, rim area, cup to disc ratio (CDR), cup volume, rim volume, linear CDR and vertical CDR between the two groups.

CONCLUSIONS

In PEX syndrome, similar decreases of the GCC and NFL occurred, and a high correlation existed between the two. Therefore, GCC can potentially be used to detect the early stages of PEX glaucoma.

[PEX syndrome. Clinical diagnosis and systemic manifestations]

As a result of demographic changes pseudoexfoliation (PEX) syndrome, an age-related systemic disorder of the extracellular matrix, will become an increasingly important issue in clinical practice. Apart from its well-known association with cataract and glaucoma, PEX syndrome predisposes to a broad spectrum of spontaneous and surgical ocular complications due to characteristic alterations of all anterior segment tissues. In view of the high risk of glaucoma development and potential complications during cataract surgery, an accurate and early diagnosis of PEX syndrome is of considerable clinical relevance. Since the characteristic central PEX deposits are lacking in up to 50 % of patients, a reliable diagnosis requires pupillary dilation. Early stages of the disease may be recognized on the basis of subtle alterations of the lens surface in addition to poor pupillary dilation and pigment-related signs including pigment dispersion and peripupillary atrophy. Any asymmetric clinical signs, e.g., regarding pupil width, pigmentation, cataract and intraocular pressure, should alert the ophthalmologist to the potential presence of PEX syndrome. Although the description of PEX syndrome as a systemic disorder of the extracellular matrix associated with the deposition of PEX material in the skin, blood vessel walls and various organ systems dates back to the early 1990s, a causal relationship between the abnormal material deposits and systemic diseases has not yet been clearly established. A growing number of smaller studies have found suggestive evidence for associations between PEX syndrome and cardiovascular/cerebrovascular diseases. The current evidence, however, is ambiguous and requires further investigation through multicenter or population-based, prospective, randomized clinical studies.

Comparison of Heidelberg retina tomography, optical coherence tomography and Humphrey visual field in early glaucoma diagnosis

OBJECTIVE

To determine the value of optic disc parameters and perimetric defects in the early diagnosis of patients with primary open-angle glaucoma (POAG).

METHODS

Optic disc parameters and perimetry were compared among patients in the early stage of POAG, patients with suspected POAG and healthy control subjects, using Heidelberg retina tomography (HRT-II), optical coherence tomography (OCT) and a Humphrey 750i automatic field analyser, in order to determine whether these parameters could be used for early POAG diagnosis.

RESULTS

A total of 55 participants were enrolled in the study. Significant differences in the optic disc parameter and perimetry values were observed between the three groups. HRT-II parameters showed good correlation with OCT parameters. The majority of the HRT-II and OCT parameters showed a good correlation with perimetry values.

CONCLUSIONS

HRT-II and OCT optic disc parameters both reflect morphological changes of the optic disc. These current findings suggest that they can both detect glaucomatous optic neuropathy earlier than a white-on-white perimetry examination. In addition, OCT can detect optic disc parameter changes that cannot be detected by HRT-II.

Scanning laser polarimetry in eyes with exfoliation syndrome

PURPOSE

To compare retinal nerve fiber layer thickness (RNFLT) of normotensive eyes with exfoliation syndrome (XFS) and healthy eyes.


METHODS

Sixty-four consecutive individuals with XFS and normal office-time intraocular pressure (IOP) and 72 consecutive healthy controls were prospectively enrolled for a cross-sectional analysis in this hospital-based observational study. The GDx-VCC parameters (temporal-superior-nasal-inferior-temporal [TSNIT] average, superior average, inferior average, TSNIT standard deviation (SD), and nerve fiber indicator [NFI]) were compared between groups. Correlation between various clinical parameters and RNFLT parameters was investigated with Spearman coefficient. 


RESULTS

The NFI, although within normal limits for both groups, was significantly greater in the XFS group compared to controls: the respective median and interquartile range (IQR) values were 25.1 (22.0-29.0) vs 15.0 (12.0-20.0), p<0.001. In the XFS group, all RNFLT values were significantly lower compared to controls (p<0.001). However, they were all within the normal clinical ranges for both groups: TSNIT average median (IQR): 52.8 (49.7-55.7) vs 56.0 (53.0-59.3) µm; superior average mean (SD): 62.3 (6.7) vs 68.8 (8.2) µm; inferior average mean (SD): 58.0 (7.2) vs 64.8 (7.7) µm, respectively. TSNIT SD was significantly lower in the XFS group, median (IQR): 18.1 (15.4-20.4) vs 21.0 (18.4-23.8), p<0.001. There was no systematic relationship between RNFLT and visual acuity, cup-to-disc ratio, IOP, central corneal thickness, Humphrey mean deviation, and pattern standard deviation in either group. 


CONCLUSIONS

Compared to control eyes, polarimetry-determined RNFLT was lower in XFS eyes with normal IOP. Therefore, close monitoring of RNFLT may facilitate early identification of those XFS eyes that convert to exfoliative glaucoma.