Increase of pallor and fluorescein-filling defects of the optic disc in the follow-up of ocular hypertensives measured by computerized image analysis

Microvascular Compromise Develops Following Nerve Fiber Layer Damage in Normal-Tension Glaucoma Without Choroidal Vasculature Involvement

PURPOSE

To investigate capillary densities in patients with unilateral normal-tension glaucoma (NTG) and normal controls using optical coherence tomography-angiography.

MATERIALS AND METHODS

We recruited 13 patients with unilateral NTG and 13 healthy controls. Optical coherence tomography-angiography was performed and pure peripapillary retinal capillary density was calculated after manually excluding large vessels and the optic disc. Paired comparison of capillary densities was performed among 3 categories of eye: NTG eye, fellow eye, and normal eye. Through vascular layer stratification we investigated differences in the retinal and choroidal circulation.

RESULTS

In total, 33 eyes of 11 unilateral NTG patients and 11 controls were analyzed. Capillary densities of NTG eyes were significantly lower than those of fellow eyes or control eyes (both P=0.013). No significant differences were found between fellow eyes and control eyes (P=0.328). Area of capillary compromise was identical to the area of retinal nerve fiber layer (RNFL) defect in all 11 eyes. In layer analysis, a decrease in capillary plexus was demonstrated only in the inner retina and no definite changes were found in the outer retina and choroid. Optic nerve head microvasculature did not show areas of capillary dropout.

CONCLUSIONS

In patients with unilateral NTG, we could observe significant retinal capillary compromise in the area of RNFL defect. No changes were demonstrated in the choroid and optic disc area. We speculated on a possibility of secondary microvascular changes in the retina to nerve damage from the wedge-shaped but not geographic shaped capillary compromise corresponding to RNFL defect area. Further studies on the optic nerve head microvasculature and blood flow are warranted to assess their relationship to glaucoma pathogenesis.

Optical Coherence Tomography Angiography of the Peripapillary Retina in Primary Angle-Closure Glaucoma

PURPOSE

To measure the change of peripapillary retinal vessel density (VD) in eyes with a history of acute primary angle-closure glaucoma (PACG).

DESIGN

Case-control study.

METHODS

Twenty-one consecutive Chinese patients with history of unilateral acute PACG were enrolled. Eyes with acute PACG constituted the case group, while the contralateral eyes without attack constituted the control. All patients underwent ophthalmic examinations including best-corrected visual acuity, intraocular pressure, and visual field (VF). Spectral-domain optical coherence tomography (SD-OCT) was used to obtain both structural OCT and OCT angiography (OCTA). Structural OCT scans provided thickness measurements of the peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC). OCTA was used to measure all-plexus peripapillary retinal VD.

RESULTS

In unaffected eyes, a dense microvascular network surrounded the disc on all-plexus retinal OCTA. The vascular network was visibly attenuated and focal capillary dropout was evident in acute PACG eyes. The peripapillary VD in acute PACG eyes was 66.6% ± 17.3% (mean ± standard deviation), which was significantly (P < .01) reduced compared to 87.2% ± 8.6% in the unaffected eyes. In acute PACG eyes, peripapillary retinal VD was positively correlated with RNFL and GCC thicknesses (P < .001 each) and negatively correlated with VF mean deviation (P = .002) and cup-to-disc ratio (P = .0064). In unaffected eyes, there were no correlations between peripapillary retinal VD and glaucoma-related parameters.

CONCLUSIONS

In acute PACG eyes, peripapillary retinal VD decreased significantly compared with the contralateral unaffected eyes. Peripapillary retinal VD was significantly correlated with other glaucomatous changes.

Arteriovenous passage times and visual field progression in normal tension glaucoma

Purpose. Fluorescein angiographic studies revealed prolonged arteriovenous passage (AVP) times and increased fluorescein filling defects in normal tension glaucoma (NTG) compared to healthy controls. The purpose of this study was to correlate baseline AVP and fluorescein filling defects with visual field progression in patients with NTG. Patients and Methods. Patients with a follow-up period of at least 3 years and at least 4 visual field examinations were included in this retrospective study. Fluorescein angiography was performed at baseline using a confocal scanning laser ophthalmoscope (SLO, Rodenstock Instr.); fluorescein filling defects and AVP were measured by digital image analysis and dye dilution curves (25 Hz). Visual field progression was evaluated using regression analysis of the MD (Humphrey-Zeiss, SITA-24-2, MD progression per year (dB/year)). 72 patients with NTG were included, 44 patients in study 1 (fluorescein filling defects) and 28 patients in study 2 (AVP). Results. In study 1 (mean follow-up 6.6 ± 1.9 years, 10 ± 5 visual field tests), MD progression per year (−0.51 ± 0.59 dB/year) was significantly correlated to the age (P = 0.04, r = -0.29) but not to fluorescein filling defects, IOP, or MD at baseline. In study 2 (mean follow-up 6.6 ± 2.2 years, 10 ± 5 visual field tests), MD progression per year (−0.45 ± 0.51 dB/year) was significantly correlated to AVP (P = 0.03, r = 0.39) but not to age, IOP, or MD at baseline. Conclusion. Longer AVP times at baseline are correlated to visual field progression in NTG. Impaired retinal blood flow seems to be an important factor for glaucoma progression.

Topography and fluorescein angiography of the optic nerve head in primary open-angle and chronic primary angle closure glaucoma

PURPOSE

The purpose of this study is to correlate optic nerve head topography with fluorescein angiography of the optic nerve head in patients with primary open-angle glaucoma (POAG), chronic primary angle closure glaucoma (CPACG), and normal controls.

METHODS

This was an institution-based, cross-sectional, case-control study of 30 consecutive patients each with POAG or CPACG, which were compared with 30 age- and sex-matched controls. The fluorescein angiograms undertaken in one eye of each of the 90 subjects were then analyzed both qualitatively and quantitatively.

RESULTS

The mean age of controls (group 1) was 51.73 +/- 9.6 years, patients with CPACG (group II) was 53.26 +/- 9.5 years, and patients with POAG (group III) was 54.5 +/- 10.4 years. The mean deviation and corrected pattern standard deviation on Humphrey visual field analyzer, respectively, were -1.51 +/- 2.01 dB and 2.09 +/- 1.04 dB the in control group, -9.4 +/- 9.3 dB and 5.32 +/- 4.02 dB in the CPACG group, and -11.27 +/- 7.7 dB and 7.57 +/- 5.34 dB in the POAG group. There was no significant difference in the disc areas between the three groups (analysis of variance [ANOVA], p = 0.157). All circulatory parameters were delayed in both glaucoma groups compared with controls with the disc filling time (ANOVA, p = 0.001) and the choroidal filling time being significantly delayed (ANOVA, p = 0.006). The Moorfield regression analysis showed good correlation with the pattern of disc fluorescence in all quadrants in cases of CPACG and POAG.

CONCLUSION

The optic nerve head and choroidal circulation was delayed in both patients with POAG and those with CPACG, which correlates with loss of neuroretinal rim and retinal nerve fiber layer on the Heidelberg Retina Tomograph II (HRT). Patients with POAG showed diffuse damage with significant rim loss, whereas patients with CPACG showed marked sectorial abnormalities (superotemporal and the inferior-temporal) on fluorescein angiography and HRT. One possible reason for this discrepancy could be sectorial ischemia occurring in cases of CPACG as a result of a sudden rise of intraocular pressure causing disc and visual field damage.

Fluorescein filling defects of the optic nerve head in normal tension glaucoma, primary open-angle glaucoma, ocular hypertension and healthy controls

BACKGROUND

To evaluate fluorescein filling defects of the optic nerve head in normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), ocular hypertension (OHT) and controls.

METHODS

Forty patients with NTG (mean age 55 +/- 10 years), 40 patients with POAG (mean age 55 +/- 11 years), 40 patients with OHT (mean age 53 +/- 13 years), and 40 age-matched controls (mean age 54 +/- 11 years) were included in a prospective study. Video fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of absolute filling defects of the optic nerve head was assessed (as a percentage of the disc area) using digital image analysis. Visual fields were tested by automatic static perimetry (Humphrey Field Analyzer, programme 24-2).

RESULTS

Absolute filling defects were significantly larger in patients with NTG (12.2 +/- 15.5%) and POAG (12.9 +/- 13.1%) compared to patients with OHT (1.2 +/- 3.6%) and healthy controls (0.1 +/- 0.5%) (p < 0.0001). The area under the receiver operating characteristic (ROC) curve was 0.806 for NTG vs healthy controls, and 0.812 for POAG vs OHT. Absolute filling defects are significantly correlated to the global indices mean deviation (r = -0.63, p < 0.0001), pattern standard deviation (r = 0.61, p < 0.0001), and corrected pattern standard deviation (r = 0.62, p < 0.0001) and significantly correlated to horizontal (r = 0.50, p < 0.0001) and vertical (r = 0.53, p < 0.0001) cup-to-disc-ratios.

CONCLUSIONS

Fluorescein filling defects of the optic disc representing capillary dropout are present in NTG and POAG. The extent of these filling defects is correlated to visual field loss and morphological damage. Fluorescein angiography may be useful in the diagnosis and management of NTG and POAG.

Role of cyclooxygenase and haemoxygenase products in nitric oxide-independent vasodilatation in the porcine ciliary artery

PURPOSE

Vascular endothelial cell dysfunction has been noted in patients with normal pressure glaucoma. Although nitric oxide (NO) accounts for a large proportion of vasorelaxation in the posterior ciliary artery, considerable relaxation remains unexplained. We investigated the roles of haemoxygenase (HO) and cyclooxygenase (COX), which produce the vasodilators carbon monoxide (CO) and prostacyclin, respectively, in NO-independent endothelium-dependent vasodilatation in porcine posterior ciliary arteries.

METHODS

Isolated vascular rings were mounted in a Mulvaney-Halpern small vessel myograph for the measurement of isometric tension development. Vasodilator responses to bradykinin (BK) were elicited in each ring on three separate occasions following preconstriction with prostaglandin F(2alpha): first in the absence of inhibitors, second in the presence of the NO synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME, 10(-3) M), and third in the presence of L-NAME and either a COX (indomethacin, 10(-6) M) or an HO inhibitor (tin protoporphyrin-IX 10(-5) M). Results were expressed as a percentage of the maximal relaxation in the presence of L-NAME alone.

RESULTS

Incubation with indomethacin (n=6), in the presence of L-NAME, significantly reduced (P<0.01) maximum BK-induced relaxation (-103.5+/-8.8%) compared to paired rings in the presence of L-NAME alone (-130.8+/-8.8%). HO inhibition did not reduce NO-independent, BK-induced relaxation when compared to paired control vessels.

CONCLUSIONS

These data suggest that in the presence of L-NAME, a COX product accounts for a significant proportion of NO-independent vasodilatation. In contrast, endogenous CO production does not have a functionally significant role in the porcine ciliary artery. Eye (2003) 17, 628-636. doi:10.1038/sj.eye.6700437

Colour Doppler imaging and fluorescein filling defects of the optic disc in normal tension glaucoma

AIM

To investigate the relation between blood flow parameters of the retrobulbar vessels measured by means of colour Doppler imaging (CDI) and fluorescein filling defects of the optic nerve head in patients with normal tension glaucoma (NTG) and control subjects.

METHODS

29 patients with NTG and 29 age and sex matched control subjects were included in this study. Blood flow velocities-peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive indices (RI) of the ophthalmic artery (OA), the central retinal artery (CRA), and of the temporal and nasal short posterior ciliary arteries (TPCA, NPCA)-were measured with CDI. Fluorescein angiograms were performed with a scanning laser ophthalmoscope. The extent of absolute fluorescein filling defects of the optic nerve head in relation to the optic nerve head was assessed.

RESULTS

The PSV of the OA, the PSV and EDV of the CRA, and of the TPCA and NPCA were significantly reduced in NTG (p<0.05). The RI of the CRA, the TPCA and NPCA were significantly increased in NTG (p<0.01). The optic nerve head fluorescein filling defects were significantly larger in NTG (p<0.01). The filling defects were significantly negatively correlated (p<0.05) with the PSV and EDV of the CRA (PSV(CRA): r = -0.41; EDV(CRA): r = -0.34), with the PSV and EDV of the NPCA (PSV(NPCA): r = -0.34; EDV(NPCA): r = -0.38), and with the EDV of the TPCA (r = -0.29). A significant positive correlation (p<0.05) was found with the RI of both PCAs (RI(NPCA): r = 0.28; RI(TPCA): r = 0.29).

CONCLUSION

Patients with NTG had reduced blood flow velocities and higher resistive indices in most retrobulbar vessels. Optic nerve head fluorescein filling defects were larger compared to controls. The filling defects were correlated with end diastolic velocities and resistive indices of the PCAs and with blood flow velocities of the CRA. Capillary loss of the optic nerve head may be related to higher downstream resistance and reduced blood flow velocities of the retrobulbar vessels.

Diagnosis and pathogenesis of glaucomatous optic neuropathy: morphological aspects

Glaucomatous optic neuropathy is classified by morphologic changes in the intrapapillary and parapapillary region of the optic nerve head and the retinal nerve fibre layer. These changes can be evaluated using descriptive optic nerve head variables which are the size and shape of the optic disc; size, shape and pallor of the neuroretinal rim; size of the optic cup in relation to the area of the disc; configuration and depth of the optic cup; cup-to-disc diameter ratio and cup-to-disc area ratio; position of the exit of the central retinal vessel trunk on the lamina cribrosa surface; presence and location of splinter-shaped haemorrhages; occurrence, size, configuration and location of parapapillary chorioretinal atrophy; diffuse and/or focal decrease of the diameter of the retinal arterioles; and visibility of the retinal nerve fibre layer. Assessment of these variables is useful for the early detection of glaucomatous optic nerve damage, to follow-up patients with glaucoma, to differentiate various types of the chronic open-angle glaucomas, and to get hints for the pathogenesis of glaucomatous optic nerve fibre loss.

Follow up of focal narrowing of retinal arterioles in glaucoma

AIM

To evaluate whether focal narrowing of retinal arterioles increases with progressive glaucomatous optic neuropathy.

METHODS

Focal narrowing of retinal arterioles and area of neuroretinal rim were morphometrically evaluated on colour stereo optic disc photographs of 59 patients with primary open angle glaucoma, 22 patients with normal pressure glaucoma, 11 patients with secondary open angle glaucoma, and 31 patients with ocular hypertension. Minimum follow up was 8 months. Focal arteriolar narrowing was quantified by calculating the ratio of the vessel width in the broadest to the narrowest vessel part.

RESULTS

In the subgroup of patients with progressive glaucomatous optic nerve damage (n = 37), focal narrowing of retinal arterioles increased significantly (p < 0.005) with decreasing neuroretinal rim area. In the subgroup of patients with stable appearance of the optic disc (n = 86), focal narrowing of retinal arterioles did not change significantly (p = 0.79). The positive correlation between increasing focal thinning of retinal arterioles and progression of glaucomatous optic neuropathy was present, although not statistically significant, in all the glaucoma subtypes examined. The location of focal thinning of retinal arterioles did not change in the follow up.

CONCLUSIONS

Focal narrowing of retinal arterioles increases significantly with progressive glaucomatous optic neuropathy, independent of the type of glaucoma. It is stable in patients with non-progressive glaucoma. The findings agree with previous reports on a higher degree of focal arteriole narrowing in eyes with pronounced optic nerve damage in comparison with those with moderate optic nerve atrophy or normal eyes. In the clinical management of patients with glaucoma, in some eyes, increasing focal arteriole narrowing may suggest progression of disease.

Ophthalmoscopic evaluation of the optic nerve head

Optic nerve diseases, such as the glaucomas, lead to changes in the intrapapillary and parapapillary region of the optic nerve head. These changes can be described by the following variables: size and shape of the optic disk; size, shape, and pallor of the neuroretinal rim; size of the optic cup in relation to the area of the disk; configuration and depth of the optic cup; ratios of cup-to-disk diameter and cup-to-disk area; position of the exit of the central retinal vessel trunk on the lamina cribrosa surface; presence and location of splinter-shaped hemorrhages; occurrence, size, configuration, and location of parapapillary chorioretinal atrophy; diffuse and/or focal decrease of the diameter of the retinal arterioles; and visibility of the retinal nerve fiber layer (RNFL). These variables can be assessed semiquantitively by ophthalmoscopy without applying sophisticated techniques. For the early detection of glaucomatous optic nerve damage in ocular hypertensive eyes before the development of visual field loss, the most important variables are neuroretinal rim shape, optic cup size in relation to optic disk size, diffusely or segmentally decreased visibility of the RNFL, occurrence of localized RNFL defects, and presence of disk hemorrhages.

Pulsatile ocular blood flow investigation in asymmetric normal tension glaucoma and normal subjects

AIMS

This study was designed to investigate pulsatile ocular blood flow (POBF) in normal tension glaucoma (NTG) patients and in normal controls. NTG patients with unilateral field loss were evaluated to compare POBF values between eyes with and without field loss.

METHODS

POBF measurements from more than 1500 subjects were collected during a period of 6 months from six optometric centres. Subjects with systemic vascular diseases (such as systemic hypertension and diabetes), ophthalmic diseases, a positive family history of glaucoma, and those individuals receiving treatment with systemic beta blockers were excluded on the basis of a questionnaire. For comparison, 95 NTG patients with unilateral field loss, selected from 403 consecutive patients with NTG, underwent POBF testing. For each individual age, sex, intraocular pressure, refraction, and pulse rate were entered into a database.

RESULTS

Data from 777 subjects were included in the analysis. POBF measurements of patients and subjects were compared allowing for differences in age, sex, intraocular pressure, refraction, and pulse rate. POBF was significantly lower in eyes of NTG patients with and without field loss (p < 0.001 and p = 0.01 respectively). Eyes of NTG patients with field loss showed significantly lower POBF than the contralateral eyes with normal field (p < 0.001).

CONCLUSIONS

POBF was significantly lower in eyes of NTG patients with and without field loss than in normal subjects, suggesting that differences in ocular blood perfusion are relevant to the development of NTG and are detectable from the early stage of the disease. Furthermore, the finding of lower POBF in NTG eyes with field loss than in the contralateral eyes with normal field suggests that haemodynamic differences between fellow eyes contribute to determine the side of onset of the disease.

Fluorescein angiographic correlation of focal narrowing of retinal arterioles in glaucoma

BACKGROUND

Recent studies have shown that focal narrowing of retinal arterioles in the parapapillary region occurs in eyes with optic neuropathies such as glaucoma. This study evaluated whether these vessel constrictions detected ophthalmoscopically have an equivalent in angiographic imaging of the fundus.

METHODS

Fluorescein angiograms and colour wide angle fundus photographs of 33 patients with open angle glaucoma and 76 subjects with normal optic nerves were examined for focal narrowing of retinal arterioles. The angiograms had primarily been taken for other reasons such as age related macula degeneration.

RESULTS

All focal narrowings of retinal arterioles detected on fundus photographs showed a localised constriction of vessel filling in the fluorescein angiograms. Degree of vessel narrowing on the fundus photographs and degree of constriction of the fluorescein vessel filling were significantly (p < 0.001) correlated with each other.

CONCLUSIONS

Focal narrowing of retinal arterioles in the parapapillary region of eyes with optic neuropathies represents a real stenosis of the vessel lumen and is not due to an ophthalmoscopic artefact.

Choroidal haemodynamics in glaucoma

AIM

Quantification of haemodynamics of the peripapillary choroid in and the assessment of possible differences between normal subjects (N), ocular hypertensive (OHT), primary open angle (POAG), and normal pressure glaucoma (NPG) patients.

METHODS

Video fluorescein angiograms (Rodenstock SLO 101) were made in 22 N subjects, 12 OHT, 48 POAG, and 46 NPG patients. The angiographically derived dye build up curves were described by means of an exponential model. One of the model parameters is the time constant tau theoretically reflecting local blood refreshment time; the blood refreshment time tau is the time needed to replace the blood volume in the choriocapillaris, inversely proportional to the local choroidal blood flow. Other variables are maximal fluorescence (Fdt) and time of first fluorescence (t0). Mean variable values were calculated for disc area and circular areas around the disc.

RESULTS

Fdt of the disc was significantly lower in the POAG and NPG patients. There was no statistical difference in t0 between the study groups. The choroidal blood refreshment time was significantly longer in NPG patients and to a lesser extent in the POAG patients compared with the normal controls. The slowest choroidal blood refreshment can be found in the NPG group. The median choroidal blood refreshment times (25th-75th percentile) in the controls, OHT, POAG, and NPG patients were 4.1 (3.7-4.5), 4.4 (3.7-6.4), 5.8 (4.3-6.8), and 7.1 (5.5-9.3) seconds respectively.

CONCLUSIONS

With the help of parametrisation of dye curves, using a one compartmental model, choroidal haemodynamics can be quantified. The blood refreshment time of the peripapillary choriocapillaris was found to be significantly prolonged especially in NPG patients; this may indicate slower choroidal haemodynamics in NPG patients.

Circulatory defects of the optic disk and retina in ocular hypertension and high pressure open-angle glaucoma

Studies using fluorescein angiography have shown that two types of circulatory defects occur in the optic disk and retina of open-angle glaucomatous eyes. The first is a defect of the microcirculation of the optic disk characterized as a fluorescein defect. Such defects begin as small areas of relatively little filling of the small vessels of the disk with fluorescein. The areas of defect show leakage for both fluorescein and indocyanine green. These defects increase in size and number with the progression of the disease. Fluorescein defects are significantly correlated with visual field loss and retinal nerve fiber layer loss. The second circulatory defect is a decrease of flow of fluorescein in the retinal vessels, especially the retinal veins, so that the greater the age, diastolic blood pressure, ocular pressure and visual field loss, the less the flow. Both the optic disk and retinal circulation defects occur in untreated ocular hypertensive eyes. These observations indicate that circulatory defects in the optic disk and retina occur in ocular hypertension and open-angle glaucoma and increase with the progression of the disease.

Automatic geometrical registration of fluorescein retinal angiograms

Changes in retinal microvascular perfusion revealed by fluorescein angiography have been reported in patients undergoing coronary artery surgery. Quantification of these changes is important and current techniques depend on careful visual inspection of the angiograms by humans. Computer image processing methods can be used to identify and highlight differences, but geometrical registration of the images is a prerequisite to the comparisons. Automatic methods for locating and matching reference points have therefore been developed. In combination with an iterative process which used least-squares error to calculate the transformation coefficients, subsets of reference points were selected and used to register successfully 20 image pairs.