Pseudoexfoliation glaucoma

Poor clinical search for the disease and dearth of published data may have been responsible in part for the as- sumed low prevalence in Nigeria and West African communities. The first study regarding pseudoexfoliation syndrome in Nigeria, published by Olawoye et al. [16] in 2012, reported its prevalence in an eye clinic in Ibadan, Nigeria. This present study determined the prevalence of pseudoexfoliation glaucoma and its characteristics in the glaucoma clinics of three tertiary eye hospitals in southwestern Nigeria. As well as adding to the fledgling literature, it is hoped that the findings will contribute to informed intervention to fill the gap in treatment for this subtype of primary open glaucoma among practicing ophthalmologists.

Compared to primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PXG) is more severe. It is associated with higher mean intraocular pressures (IOP) with higher IOP fluctuations, higher frequency and severity of optic nerve damage, more rapid visual field loss and increased glaucoma medication resistance and a greater necessity for surgical intervention 8 .The purpose of current study was to document the ocular clinical profile of patients with pseudoexfoliation syndrome and pseudoexfoliation glaucoma.

Pseudoexfoliation syndrome (PXF) was first reported by Lindberg in 1917 in a Finnish population [1]. It is char- acterized by the deposition of a distinctive fibrillar mate- rial in the anterior segment of the eye. Pseudoexfoliation syndrome is frequently associated with open angle glau- coma, known as pseudoexfoliation glaucoma, which is the most common identifiable form of secondary open angle glaucoma worldwide [2]. Pseudoexfoliation is a known risk factor for developing cataracts [3]. Compli- cating factors such as poor mydriasis, zonular weakness, corneal endothelial dysfunction, higher rate of vitreous loss, capsular phimosis, and opacification have all been reported after cataract surgery [4,5]. Pseudoexfoliation is considered to be a systemic disorder, pseudoexfoliative material has been reported in lungs, skin, liver, heart, kidney, gallbladder, blood vessels, extra ocular muscles

Study design/patients and methods: Sixty patients (60 eyes) participated in the study. Glaucoma patients (POAG or PXFG) scheduled for treatment with SLT were included. Inflammation was measured with a laser flare meter (Kowa FM-500). Measurements were made before SLT and 2 hours, 1 week, and 1 month after SLT treatment. IOP was also checked at the same time intervals.

Introduction: Measurements of intraocular pressure (IOP) with Goldmann applanation tonometry are affected by central corneal thickness (CCT), as thinner corneas underestimate and thicker corneas overestimate the true IOP value. The literature is controversial regarding CCT values in patients with primary open-angle glaucoma (POAG) and exfoliation glaucoma (XFG). The aim of this study was to evaluate CCT in patients with XFG and POAG.

Inclusion criteria for POAG patients were intraocular pressure over 22 mmHg on at least two measurements, an open anterior chamber angle determined with gonioscopy, and visual field and optic nerve changes consistent with glaucoma. Presence of exfoliation material in the anterior chamber, together with glaucoma criteria, established the diagnosis of PXFG. Control subjects had no evidence of exfoliative material at the anterior lens capsule or pupillary margin, and had intraocular pressure of less than 22 mmHg. Control subjects had normal visual fields, an open anterior chamber angle, no evidence of glaucomatous changes in the optic disc, and no history of glaucoma or ocular hypertension in first- degree relatives. Subjects with pseudoexfoliation syndrome (with or without ocular hypertension) or ocular hypertension were excluded from the study. The nutritional status of both patients and controls was assessed using the Subjective Global

devices which target the natural outflow pathways of aqueous humor. Overall, our results indicate a strong IOP-lowering effect after XEN45 implantation which can be achieved in POAG patients as well as in PXG patients and is almost comparable to that of conven- tional filtrating glaucoma surgery [6], although how- ever, in the absence of a prospective, randomized trial, it is difficult to draw any major conclusions versus tra- beculectomy. At the same time, typical safety risks of traditional incisional glaucoma surgery, such as hypotony-related complications, scarring, foreign body reaction, cataract formation, and surgically induced astigmatism are almost negligible in this ab-interno procedure. Therefore, given the marked and enduring IOP-lowering effect of the XEN45 and its reliable safety profile, this micro-invasive procedure might be consid- ered at an earlier stage of glaucoma disease than con- ventional filtrating glaucoma surgery. Especially in PXG patients, who often respond only weakly to medical therapy and exhibit rapid disease progression [23], this approach may help to achieve a low target IOP with re- duced medication at an earlier stage. Moreover, this strategy would preserve the conjunctiva if further glau- coma filtrating surgery interventions might be required to control IOP more efficiently.

Most studies have utilized AH to estimate the level of TNF- α in glaucoma patients. Currently, there is no evidence directly correlating the level of cytokines in the eyes and serum/plasma. We estimated plasma level of TNF- α in well- defined PEG patients and compared to controls (no PEG or any ophthalmic disease as established by full ophthalmic examination). Age is an issue of particular importance to TNF- α level as age-related increases in TNF- α systemic levels could provide a basis for atherosclerosis, type diabetes and Alzheimer’s disease in older individuals. 23 Thus, our con-

The primary outcome of this clinical trial was to evaluate the IOP response to SLT in patients without requiring any antiglau- coma medications or additional laser or surgical therapy. Eyes were considered successes as long as the IOP did not return to baseline (,3 mmHg) and/or no further medical, laser, or surgi- cal intervention for the treatment of glaucoma was initiated. Eyes were included in the analysis of each time interval until an intervention occurred, at which point they were considered failures and removed from subsequent follow-up periods. Patients were excluded from analysis at any subsequent fol- low-up interval if they underwent cataract surgery or failed to reach the specified follow-up exam interval.

antiglaucoma medications between the two glaucoma groups. Both surgical strategies were effective in reducing IOP and the mean IOP levels remained stable during the three years of follow-up. Both procedures were also able to eliminate the need for antiglaucoma medications in many eyes over the entire study period. These results suggest that bleb function was maintained in a high proportion of all operated eyes.

Methods: This was a prospective open-label study. Twenty-four consecutive patients with PEX glaucoma were included. Twelve patients underwent cataract surgery and AIT (triple-surgery group), and 12 patients underwent only AIT (single-surgery group). In each eye, IOP fluctuations over 24 h were measured with the contact lens sensor before and at 3 months after the surgery. We compared the change of IOP fluctuation before and after operation. We also evaluated the difference in IOP changes between the triple- and single-surgery groups.

Results. Some difference was found in intraocular pressure between the PEX group and the control group and between the pseudoexfoliation glaucoma group and the control group, but no significant difference was found between the 2 study groups. There was a significant difference in the incidence of some degree of pigmentation in the anterior chamber angle and no difference in the widths of the angle between each group. A significant positive relationship was observed between intraocular pressure and the degree of pig- mentation of the anterior chamber angle in both the PEX group and the pseudoexfoliation glaucoma group. Conclusions. The results of this study indicate that the amount of pigmentation and exfoliation material in the anterior segment significantly correlates with the level of IOP and possibly with the degree of trabecular dysfunction. It seems that for clear identification of PEX and pseudoexfoliation glaucoma factors, clinical assessment appears to be insufficient.

Pseudoexfoliation syndrome (PXS) is a systemic condition with eye manifestations. In the eye, pseudoexfoliation material deposits on various structures of the anterior segment. The nature of this material is mostly fibrillar with fibers made up of microfibrils and coated with amorphous material. The composition of these fibrils is diverse and includes basement membrane components as well as enzymes involved in extracellular matrix maintenance. Pseudoexfoliation is the most common cause of secondary open-angle glaucoma (pseudoexfoliation glaucoma, PXG) worldwide. The goal of this review is to summarize our knowledge on the genetics of this systemic disorder and its resultant ocular manifestations. PXS familial aggregation suggests genetic inheritance. PXS has been strongly associated with single nucleotide polymorphisms (SNPs) of the lysyl oxidase-like 1 (LOXL1) gene on chromosome 15q24.1. Two of these SNPs confer a higher than 99% population attributable risk for PXS and PXG in the Nordic population; however, they carry different risks in different populations. The high risk haplotypes also vary among different populations. LOXL1 is one of group of the enzymes involved in the cross-linking of collagen and elastin in the extracellular matrix. Its function in connective tissue maintenance has been confirmed in mice; however, its actual role in PXS remains unclear. Contactin-associated protein-like 2 also has a strong genetic association with PXS in a German cohort and is an attractive candidate molecule. It encodes for a protein involved in potassium channel trafficking. Other candidate genes linked to PXS include lysosomal trafficking regulator, clusterin, adenosine receptors, matrix metalloproteinase-1 (MMP1), and glutathione transferase. These genes may be modifying genes for development of PXS and PXG.

The second difference is the occurrence of plaques of material seen in primary glaucoma 27 . These plaques are actually fibrillar tendons with their surrounding collagen sheaths, running through juxtacanalicular tissue. When histological sections are cut in the usual radial orientation (sagittal sections), the tendon and sheaths appear as discontinuous plaques, whereas in tangential section they appear as tendons. The tendon sheaths become thicker with age and are especially thick in primary glaucoma, appearing as an increase in plaque material when viewed with the standard sagittal histologic sections. Pseudoexfoliation glaucoma eyes do not have this excess tendon sheath or plaque material but rather have amounts similar to control eyes 26 . This indicates a fundamental difference in the nature of pseudoexfoliative glaucoma and of primary glaucoma.

which was placed in an unmarked and closed envelope. The inclusion criteria for the study were: being older than 18 years of age; having a history of glaucoma with subtypes POAG, pseudoexfoliation glaucoma, pigmentary glaucoma, or OHT; patients who underwent a successful phacoemulsification- assisted cataract excision surgery with intracapsular lens implantation; and patients who underwent a laser treatment (SLT or ALT) not less then 3 months and not more then 6 months following the cataract surgery. The reason for performing the laser treatment less than 3 months since the cataract extraction phacoemulsification was to allow for complete healing, such as intracapsular fibrosis and reduction in inflammatory response. This interval would also enable the achievement of a stability in change of anterior chamber depth, an angle opening distance at 500 µ m anterior to the scleral spur, and reduction in IOP at various time points (1, 3, and 6 months) after cataract extraction, as shown by various studies, such as the one by Huang et al. 20

Recurrent episodes of raised IOP because of an intermittent or subacute angle closure. The angle becomes narrow & narrow at intervals due to pupillary block. But the aqueous manages to sweeps into the anterior chamber by breaking the pupillary block spontaneously. So IOP becomes normal at the time of presentation. Repeated attacks may lead to chronic glaucoma hence early iridotomy is needed in these patients even though IOP may be normal at presentation. Signs and symptoms are only mild and hence most patients do not seek medical counsel at early stage.

SFRP1 is an antagonist of the Wnt signaling pathway, which has been localized in many cells and tissues [27], including the human TM [28]. By preventing Wnt from activating its receptor, SFRP1 blocks the Wnt effects on normal cellular functions and decreases the intracellular level of catenin. In cultured TM cells derived from POAG patients, SFRP1 expression was significantly higher than non-glaucoma controls, concomitant with a decrease in catenin level [29]. Treatment of ex vivo per- fused human anterior segments with recombinant SFRP1 reduced AH outflow facility [29]. Intravitreal in- jection of adenoviral vector encoding SFRP1 increases ocular expression of the protein and raises IOP in the mouse [28, 29], clearly indicating a potential contribu- tory role in glaucoma. However, SFRP1 levels in AH of glaucoma patients have not been reported.

Initially, these devices drain aqueous humor from the ante- rior chamber to the posterior plate; the aqueous humor then crosses the pseudocyst formed around this plate and is sub- sequently absorbed by venous capillaries, or the lymphatic system. 2 – 5 The Ahmed valve (New World Medical, Inc., Rancho Cucamonga, CA) creates a fl ow-restriction, and is speci fi cally manufactured for patients with refractory glau- coma; these cases are associated with a high risk of failure when trabeculectomy is carried out, along with a high risk of persistent high intraocular pressure. 6–10 The size of the Ahmed valve plate placed close to the equator is 184 mm. 211 The Ahmed glaucoma valve (AGV), a unidirectional valve, has been shown to be bene fi cial for the prevention of hypotony and choroidal haemorrhage in the fi rst few weeks after surgery. 12,13 However, the AGV is known to fail on occasion, primarily due to the formation of blebs around the plate as a direct result of scar formation. Following valve surgery, a large number of patients require glaucoma medications in order to control intrao- cular pressure (IOP) within normal the normal range. 6,9,14 Furthermore, the intraoperative application of mito- mycin-c during the implantation of an AGV does not prevent, or inhibit, the formation of scar tissue around the plate. 15 Previous data also indicate that the surgical implantation of an AGV creates a resistance to aqueous fl ow, thus reducing the chances of long-term success. 16 The current consensus of opinion is that bleb-related in fl ammation and scarring observed after the implanta- tion of an AGV could be related to the biomaterial that is used to construct the Ahmed valve plate. Research has shown that AGVs will induce less in fl ammation if they are manufactured with silicone plates, rather than poly- propylene plates. 17,18

We didn’t find adequate published data from the SSA region on CCT among PXG and PACG patients for comparison with our results. There are conflicting re- ports on the differences of mean CCT between patients with PXG and other diagnostic groups, particularly POAG. Similar to some reports from Europe [25, 28], we found no statistically significant difference of CCT between PXG and POAG subjects. Some studies from other regions have shown PXG eyes to have thinner CCT compared to POAG and normal eyes [19, 29, 30], while others found thicker CCT in PXG compared to POAG eyes. Although our PXG patients had older mean age (which was associated with thinner CCT) and higher IOP, these were not found to affect the overall CCT on regres- sion analysis. A study from central Ethiopia reported CCT in PXG eyes of 579.00 μm [17]. However, there were only 4 PXG eyes included in the study, with surgery also a possibility to have affected the results. More studies from different regions, with comparison of CCT in sub- sets of patients with pseudoexfoliative syndrome (with and without glaucoma), POAG and normal controls would better provide more definitive information. With

In our study, we did not include patients with glaucoma in order to identify PXF as an independent risk factor from glaucoma in the development of CRVO. It is not needed to develop PXF glaucoma in order for PXF to be a risk factor for CRVO, according to our results. In a study of ocular hemodynamics in patients with PXF and pseudoexfoliative glaucoma, it was found that blood flow in retinal and bulbar vessels is compromised even in PXF patients without glau- coma in comparison to controls. 15 This decrease in retrobulbar