Karine D. Bojikian

The Effect of Phacoemulsification on Intraocular Pressure in Medically Controlled Open-Angle Glaucoma Patients

PURPOSE To evaluate intraocular pressure (IOP) after phacoemulsification in patients with medically controlled open-angle glaucoma (OAG), and examine the association of biometric variables to IOP changes. DESIGN Retrospective case series. METHODS Open-angle glaucoma patients without prior incisional glaucoma surgery undergoing phacoemulsification by a single surgeon between January 1997 and October 2011 were evaluated. Patient charts were reviewed to obtain demographic information, preoperative glaucoma medications, severity and treatment measures, and preoperative and postoperative IOP. RESULTS A total of 157 eyes (157 patients) were included in the study. The average preoperative IOP of 16.3 ± 3.6 mm Hg decreased to 14.5 ± 3.4 mm Hg at 1 year (P < .001). Sixty eyes (38%) required additional medications or laser for IOP control within the first year postoperatively, or had a higher IOP at postoperative year 1 without medication change. Among eyes without postoperative medication changes (n = 102), higher preoperative IOP (P < .001), older age (P = .006), and deeper anterior chamber depth (P = .015) were associated with lower postoperative IOP. CONCLUSIONS Phacoemulsification resulted in a small average decrease in IOP in patients with OAG. A sizeable proportion of medically controlled glaucoma patients with open angles undergoing phacoemulsification experienced an increase in IOP or required more aggressive treatment to control IOP postoperatively.

Peripapillary Retinal Nerve Fiber Layer Vascular Microcirculation in Glaucoma Using Optical Coherence Tomography–Based Microangiography

Purpose To investigate the vascular microcirculation changes in the retinal nerve fiber layer (RNFL) in normal, glaucoma suspect, and open-angle glaucoma (OAG) groups using optical coherence tomography–based microangiography (OMAG). Methods One eye from each subject was scanned with a Cirrus HD-OCT 5000–based OMAG prototype system montage scanning protocol centered at the optic nerve head (ONH). Blood flow signals were extracted using OMAG algorithm. Retinal nerve fiber layer vascular microcirculation was measured by calculating the blood flux index and vessel area density within a 1.2-mm width annulus centered at the ONH with exclusion of big retinal vessels. One-way ANOVA were performed to analyze the RNFL microcirculation among groups. Linear-regression models were constructed to analyze the correlation between RNFL microcirculation and clinical parameters. Discrimination capabilities of the flow metrics were assessed with the area under the receiver operating characteristic curve (AROC). Results Twenty normal, 26 glaucoma suspect, and 42 OAG subjects were enrolled. Eyes from OAG subjects and glaucoma suspects showed significantly lower blood flux index compared with normal eyes (P ≤ 0.0015). Retinal nerve fiber layer blood flow metrics showed significant correlations with visual field indices and structural changes in glaucomatous eyes (P ≤ 0.0123). Similar discrimination capability of blood flux index compared with RNFL thickness was found in both disease groups. Conclusions Peripapillary RNFL vascular microcirculation measured as blood flux index by OMAG showed significant differences among OAG, glaucoma suspect, and normal controls and was significantly correlated with functional and structural defects. Retinal nerve fiber layer microcirculation measurement using OMAG may help physicians monitor glaucoma.

Optic nerve head perfusion in normal eyes and eyes with glaucoma using optical coherence tomography-based microangiography.

BACKGROUND To investigate the differences of perfusion in the optic nerve head (ONH) between normal and glaucomatous eyes using optical microangiography (OMAG) based optical coherence tomography (OCT) angiography technique. METHODS One eye from each subject was scanned with a 68 kHz Cirrus 5000 HD-OCT-based OMAG prototype system centered at the ONH (Carl Zeiss Meditec Inc, Dublin, CA, USA). Microvascular images were generated from the OMAG dataset by detecting the differences in OCT signal between consecutive B-scans. The pre-laminar layer (preLC) was isolated by a semi-automatic segmentation program. En face OMAG images for preLC were generated using signals with highest blood flow signal intensity. ONH perfusion was quantified as flux, vessel area density, and normalized flux within the ONH. Standard t-tests were performed to analyze the ONH perfusion differences between normal and glaucomatous eyes. Linear regression models were constructed to analyze the correlation between ONH perfusion and other clinical measurements. RESULTS Twenty normal and 21 glaucoma subjects were enrolled. Glaucomatous eyes had significantly lower ONH perfusion in preLC in all three perfusion metrics compared to normal eyes (P≤0.0003). Significant correlations between ONH perfusion and disease severity as well as structural changes were detected in glaucomatous eyes (P≤0.012). CONCLUSIONS ONH perfusion detected by OMAG showed significant differences between glaucoma and normal controls and was significantly correlated with disease severity and structural defects in glaucomatous eyes. ONH perfusion measurement using OMAG may provide useful information for detection and monitoring of glaucoma.

Risk factors for acute postoperative intraocular pressure elevation after phacoemulsification in glaucoma patients

Purpose To evaluate the risk factors for and frequency of an acute intraocular pressure (IOP) elevation (spike) after phacoemulsification in patients with glaucoma. Setting Academic glaucoma clinics and operating rooms. Design Retrospective case series. Methods Charts of consecutive glaucoma patients without previous incisional glaucoma surgery having phacoemulsification by the same surgeon between August 1996 and July 2012 were reviewed to obtain demographic information, preoperative glaucoma medications, severity and treatment measures, intraoperative course, and postoperative outcomes. A postoperative IOP spike was defined as IOP greater than 50% above baseline IOP. Main outcome measures were the number of eyes with a postoperative IOP spike and risk factors associated with an IOP spike after phacoemulsification. Results Of 271 eyes (271 patients) included in the study, 45 (17%) had an IOP spike. Risk factors for postoperative IOP spike by multivariate analysis included longer axial length (AL) or associated characteristics (wider angle grade on gonioscopy, deeper anterior chamber, and male sex), higher number of preoperative IOP‐lowering medications, previous laser trabeculoplasty, and lack of postoperative oral acetazolamide. One eye (0.4%) required trabeculectomy during the 90‐day postoperative period. Conclusions A significant proportion of glaucoma patients having phacoemulsification had an IOP spike. Patients requiring a higher number of IOP‐lowering medications or laser trabeculoplasty for IOP control preoperatively and those with a greater AL should be treated more aggressively with IOP‐lowering medication in the immediate postoperative period. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Peripapillary Retinal Nerve Fiber Layer Vascular Microcirculation in Eyes With Glaucoma and Single-Hemifield Visual Field Loss

Importance Understanding the differences in vascular microcirculation of the peripapillary retinal nerve fiber layer (RNFL) between the hemispheres in eyes with glaucoma with single-hemifield visual field (VF) defects may provide insight into the pathophysiology of glaucoma. Objective To investigate the changes in the microcirculation of the peripapillary RNFL of eyes with glaucoma by using optical microangiography. Design, Setting, and Participants Eyes with glaucoma and single-hemifield VF defect and normal eyes underwent scanning using an optical microangiography system covering a 6.7 × 6.7-mm2 area centered at the optic nerve head. The RNFL microcirculation was measured within an annulus region centered at the optic nerve head divided into superior and inferior hemispheres. Blood flux index (the mean flow signal intensity in the vessels) and vessel area density (the percentage of the detected vessels in the annulus) were measured. Main Outcomes and Measures Differences in microcirculation between the hemispheres in eyes with glaucoma and normal eyes and correlations among blood flow metrics, VF thresholds, and clinical optical coherence tomography structural measurements were assessed. Results Twenty-one eyes from 21 patients with glaucoma (7 men and 14 women; mean [SD] age, 63.7 [9.9] years) and 20 eyes from 20 healthy control individuals (9 men and 11 women; mean [SD] age, 68.3 [10.7] years) were studied. In eyes with glaucoma, the abnormal hemisphere showed a thinner RNFL (mean [SE] difference, 23.5 [4.5] &mgr;m; 95% CI, 15.1-32.0 µm; P < .001), lower RNFL blood flux index (mean [SE] difference, 0.04 [0.01]; 95% CI, 0.02-0.05; P < .001), and less vessel area density (mean [SE] difference, 0.08% [0.02%]; 95% CI, 0.05%-0.10%; P < .001) than did the normal hemisphere. Compared with normal eyes, reduced RNFL microcirculation was found in the normal hemisphere of eyes with glaucoma, measured by mean [SE] differences in blood flux index (0.06 [0.01]; 95% CI, 0.04-0.09; P < .001) and vessel area density (0.04% [0.02%]; 95% CI, 0.02%-0.08%; P = .003) but not in RNFL thickness (3.4 [4.7] &mgr;m; 95% CI, −6.2 to 12.9 µm; P = .48). Strong correlations were found between the blood flux index and VF mean deviation (Spearman &rgr; = 0.44; P = .045) and RNFL thickness (Spearman &rgr; = 0.65; P = .001) in the normal hemisphere of the eye with glaucoma. Conclusions and Relevance Reduced RNFL microcirculation was detected in the normal hemisphere of eyes with glaucoma, with strong correspondence with VF loss and RNFL thinning. Although the results suggest that vascular dysfunction precedes structural changes seen in glaucoma, longitudinal studies would be needed to confirm this finding.

Repeatability and reproducibility of optic nerve head perfusion measurements using optical coherence tomography angiography

Abstract. Optical coherence tomography angiography (OCTA) has increasingly become a clinically useful technique in ophthalmic imaging. We evaluate the repeatability and reproducibility of blood perfusion in the optic nerve head (ONH) measured using optical microangiography (OMAG)-based OCTA. Ten eyes from 10 healthy volunteers are recruited and scanned three times with a 68-kHz Cirrus HD-OCT 5000-based OMAG prototype system (Carl Zeiss Meditec Inc., Dublin, California) centered at the ONH involving two separate visits within six weeks. Vascular images are generated with OMAG processing by detecting the differences in OCT signals between consecutive B-scans acquired at the same retina location. ONH perfusion is quantified as flux, vessel area density, and normalized flux within the ONH for the prelaminar, lamina cribrosa, and the full ONH. Coefficient of variation (CV) and intraclass correlation coefficient (ICC) are used to evaluate intravisit and intervisit repeatability, and interobserver reproducibility. ONH perfusion measurements show high repeatability [CV≤3.7% (intravisit) and ≤5.2% (intervisit)] and interobserver reproducibility (ICC≤0.966) in all three layers by three metrics. OCTA provides a noninvasive method to visualize and quantify ONH perfusion in human eyes with excellent repeatability and reproducibility, which may add additional insight into ONH perfusion in clinical practice.

Incidence and risk factors for traumatic intraocular pressure elevation and traumatic glaucoma after open-globe injury.

PurposeTo examine traumatic intraocular pressure (IOP) elevation and glaucoma after open-globe injury.DesignRetrospective, observational case series.MethodsReview of patients with open-globe repair at the University of Washington from May 1997 through July 2010. Traumatic IOP elevation and glaucoma were defined respectively as intraocular pressure (IOP) ≥22 mm Hg at >1 visit or need for glaucoma medication, and long-term (at least 3 months) glaucoma medication use or glaucoma surgery.ResultsWe included 515 eyes (515 patients). The mean follow-up was 12.6±20.1 months. One hundred twenty eyes (23.3%) developed traumatic IOP elevation, of which 32 (6.2%) developed glaucoma; six eyes (1.2%) required glaucoma surgery. The mean time to development of traumatic IOP elevation was 1.5±3.4 months (range 1 day to 2 years). Kaplan–Meier 6- and 12-month estimates for development of traumatic IOP elevation were 27.2 and 32.4%, respectively, and for development of traumatic glaucoma were 7.1 and 11.0%, respectively. Multivariate regression revealed associations between traumatic IOP elevation and older age, and traumatic glaucoma and prior penetrating keratoplasty, initial vitreous hemorrhage, Zone II injury, and penetrating keratoplasty after open-globe repair. Traumatic glaucoma was controlled (IOP <22 mm Hg) in 78.1% of eyes at final follow-up, with mean IOP of 18.2 mm Hg on 1.7 medications.ConclusionsTraumatic IOP elevation and glaucoma were common after visually salvageable open-globe injury. Most cases developed within 6 months, although longer follow-up remains important for case detection. Penetrating keratoplasty before or after repair, and vitreous hemorrhage were notable risk factors.

Optic Disc Hemorrhage after Phacoemulsification in Patients with Glaucoma

Background. Optic disk hemorrhage is known to be a risk factor for glaucoma progression. Cataract surgery by phacoemulsification results in large intraocular pressure fluctuations. We aim to investigate whether phacoemulsification is associated with optic disc hemorrhage in patients with glaucoma. Methods. This is a retrospective review of consecutive university clinic based glaucoma patients undergoing phacoemulsification alone, with at least 3 visits in the year before and at least 5 visits in the year following phacoemulsification. The presence of optic disk hemorrhage was evaluated with slit lamp biomicroscopy at each clinic visit prior to and following phacoemulsification. Results. We evaluated 158 eyes of 158 subjects; 15 (9.5%) had ODH noted at least once during the 2-year study period. Four eyes had ODH identified on postoperative day 1, for a cross-sectional prevalence of 2.5%. Fourteen ODH episodes were noted preoperatively versus 12 episodes postoperatively (P = 0.68). Aspirin use was associated with ODH (P = 0.015). Conclusions. Our cross-sectional study found a prevalence of ODH immediately after CE that was similar to other published rates, and our longitudinal study did not find an increase in ODH in the year after phacoemulsification when compared to the year prior to surgery.

Refractive Outcome of Cataract Surgery in Eyes With Prior Trabeculectomy: Risk Factors for Postoperative Myopia.

Purpose: To examine refractive outcomes after phacoemulsification in eyes with prior trabeculectomy. Design: Retrospective observational case-control study Methods: Comparison of eyes of glaucoma patients undergoing cataract surgery after trabeculectomy (study group) with a matched group with medically controlled glaucoma (control group). Laser interferometry was used to obtain ocular biometry. We measured the difference between the expected and actual postoperative refraction using third-generation and fourth-generation intraocular lens (IOL) prediction formulae (Haigis, Holladay 2, Hoffer Q, and SRK-T). A residual difference of >1.0 D of hyperopia or myopia was considered a “refractive surprise.” Results: In total, 86 eyes (85 patients) were included, including 23 eyes (22 patients) in the study group and 63 eyes (63 patients) in the control group. The mean follow-up was 12.2±4.1 months. Eyes (n=13) with trabeculectomy and a preoperative intraocular pressure (IOP)⩽9 mm Hg had significantly more large myopic surprises than the control group for all IOL formulae (P=0.015 Haigis, P=0.003 Holladay 2, P=0.004 Hoffer Q, P=0.003 SRK-T). Eyes (n=10) with trabeculectomy and preoperative IOP>9 mm Hg, however, did not have significantly more myopic errors than the control (P>0.05, all formulae). An “IOP spike” defined as a >50% rise in IOP from baseline within 1 month of cataract surgery in the subgroup with preoperative IOP⩽9 mm Hg (n=8) was associated with increased risk of large myopic surprise (3/8 subset vs. 1/63 control eyes for all formulae; P=0.004 Haigis, P=0.004 Holladay 2, P=0.001 Hoffer Q, P=0.004 SRK-T) as well as for large myopic and hyperopic surprises overall (4/8 subset vs. ⩽2/63 depending upon formulae; all P⩽0.001). Conclusions: Low posttrabeculectomy IOP (⩽9 mm Hg) is a risk factor for significant myopic surprise when undergoing subsequent cataract surgery despite using laser interferometry to measure ocular biometry and later generation formulae to determine IOL power. In addition, an IOP spike was associated with a 50% risk for large refractive surprise in this low IOP group.

Lamina depth and thickness correlate with glaucoma severity

Purpose: To evaluate the correlation between lamina cribrosa (LC) morphology and glaucoma severity in patients with primary forms of open-angle glaucoma (OAG) using enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT) and Humphrey visual field test (HVF). Subjects and Methods: Patients with OAG (n = 166), divided into normal-tension glaucoma (NTG) and high-tension glaucoma (HTG) groups (n = 66 and n = 100), were imaged using SD-OCT to obtain horizontal B-scan images of the optic nerve head (ONH). Laminar depth (LD) and laminar thickness (LT) were measured at the center of ONH. Results: The mean (±standard deviation) values of LD, LT, and visual field mean deviation (MD) were 555.4 ± 142.3 μm, 179.9 ± 49.7 μm, and − 5.7 ± 6.4 dB, respectively. In the multivariate linear regression analysis, LD, LT, and intraocular pressure (IOP) were significantly correlated with MD (P = 0.007, P = 0.037, and P = 0.004, respectively). In the subgroup analyses, only LD was associated with MD in the NTG group (n = 66), whereas LT and IOP were correlated with MD in the HTG group (n = 100). Neither axial length nor central corneal thickness was associated with LD or LT. Conclusions: Glaucoma severity, as measured by HVF MD, shows significant correlations with LD and LT, with greater severity associated with increasing LD and decreasing LT. Normal- and high-tension OAG patients have different associations with LD and LT, which implies that the pathogenesis of these two entities might be different.