Steady-state pattern electroretinogram and frequency doubling technology in anisometropic amblyopia.

BACKGROUND: Steady-state pattern electroretinogram (PERG) and frequency doubling technology (FDT) perimetry can be used to selectively investigate the activity of the M-Y ganglion cells in adult anisometropic amblyopes. METHODS: Fifteen normal subjects (mean 27.8±4.1 years) and 15 adults with anisometropic amblyopia (mean 28.7±5.9 years) were analyzed using steady-state PERG and FDT. RESULTS: The amplitude of steady-state PERG was significantly different not only among the control group and both the amblyopic eye (P=0.0001) and the sound eye group (P=0.0001), but also between the latter two groups (P=0.006). The difference in FDT mean deviation was statistically significant not only between the control group and amblyopic eye group (P=0.0002), but also between the control group and the sound eye group (P=0.0009). The FDT pattern standard deviation was significantly higher in the control group rather than in the amblyopic eye (P=0.0001) or the sound eye group (P=0.0001). A correlation was found between the reduction in PERG amplitude and the increase in FDT-pattern standard deviation index not only in amblyopic (P=0.0025) and sound (P=0.0023) eyes, but also in the healthy control group (P=0.0001). CONCLUSION: These data demonstrate that in anisometropic amblyopia, there is an abnormal functionality of a subgroup of the magnocellular ganglion cells (M-Y), and the involvement of these cells, together with the parvocellular pathway, may play a key role in the clinical expression of the disease.

ET-1 Plasma Levels, Aqueous Flare, and Choroidal Thickness in Patients with Retinitis Pigmentosa.

Purpose. To assess endothelin-1 (ET-1) plasma levels, choroidal thickness, and aqueous flare in patients with early stage retinitis pigmentosa (RP) and to search for possible correlations. Methods. We compared 24 RP patients with 24 healthy controls. Choroidal thickness and aqueous flare were measured, respectively, by using a spectral domain optical coherence tomography and a laser flare-cell meter, whereas plasma samples were obtained from each patient to evaluate ET-1 plasma levels. Results. Notably, RP subjects showed significantly increased ET-1 plasma levels and reduced choroidal thickness compared with controls: 2.143 ± 0.258 versus 1.219 ± 0.236 pg/mL, P < 0.002, and 226.75 ± 76.37 versus 303.9 ± 39.87 µm, P < 0.03, respectively. Higher aqueous flare values were also demonstrated in RP compared to controls: in detail, 10.51 ± 3.97 versus 5.66 ± 1.29 photon counts/ms, P < 0.0001. Spearman's correlation test highlighted that the increase of ET-1 plasma levels was related with the decrease of choroidal thickness (r = -0.702; P < 0.023) and the increase of aqueous flare (r = 0.580; P < 0.007). Conclusions. Early stage RP patients show a breakdown of blood-ocular barrier and increased ET-1 plasma levels and these findings may contribute to the reduction of choroidal thickness.

Hemifield pattern electroretinogram in ocular hypertension: comparison with frequency doubling technology and optical coherence tomography to detect early optic neuropathy.

BACKGROUND: To assess the sensitivity and specificity of hemifield pattern electroretinogram (HF-PERG) for detecting early retinal ganglion cell (RGC) damage in ocular hypertensive (OH) patients. METHODS: Fifty-two OH patients (mean age 56±9.6 years) with an intraocular pressure (IOP) .21 mmHg were assessed. All subjects underwent HF-PERG, optical coherence tomography (OCT), and frequency doubling technology (FDT) visual field. RESULTS: OH patients showed a significant increase of peak-time of the N95 (P=0.027) compared to controls. The amplitude of the N95 of the lower and upper HF-PERG showed significant differences (P=0.037 and P=0.023, respectively) between the two groups. A significant intraocular (P=0.006) and interocular (P=0.018) asymmetry of N95 amplitude was found. Receiver operating characteristic (ROC) curve analysis revealed a sensitivity of 93% for the N95 of the lower HF-PERG, whereas full-field pattern electroretinogram (PERG) N95 peak-time had a sensitivity of 88%. In OH patients, we found a thinning of OCT - retinal nerve fiber layer (RNFL), especially in the superior and inferior quadrant, although not statistically significant, and a significantly higher FDT pattern standard deviation (FDT-PSD; P=0.001). In the OCT-RNFL inferior quadrant, a sensitivity of 82% was recorded. Finally, the sensitivity of the FDT-PSD was 92%. CONCLUSION: Our study shows that HF-PERG is a very sensitive test for detecting early damage of the RGC.

Influence of age and gender on corneal biomechanical properties in a healthy Italian population.

PURPOSE: The aim of this study was to assess corneal hysteresis (CH) and corneal resistance factor (CRF) in healthy subjects, to evaluate the relationship with age, and to investigate possible associations with other ocular factors. METHODS: Four hundred Italian subjects (male-to-female ratio, 168:232; mean age, 58.8 ± 17.2 years) were included and divided into 5 subgroups based on age. CH, CRF, and central corneal thickness (CCT) were measured by using the Ocular Response Analyzer and the integrated handheld pachymeter, and their relationship with gender, age, and ocular factors was evaluated. RESULTS: The mean CH, CRF, and CCT values were 10 ± 1.6 mm Hg, 10.5 ± 1.7 mm Hg, and 532.2 µm, respectively. Women had a lower mean CH (9.9 vs. 10.2 mm Hg; P = 0.04) and CRF (10.3 vs. 10.8 mm Hg; P = 0.03) than did men. The youngest subjects had the highest CH (11.2 ± 1.5 mm Hg), whereas the oldest patients had the lowest CH values (9 ± 1.1 mm Hg). No significant differences in CRF were observed between age groups. CH and CRF showed a positive correlation (r = 0.58; P < 0.001), and both had a positive association with CCT (r = 0.27; P < 0.001 and r = 0.57; P < 0.001, respectively). The strongest correlations were observed between Goldmann-correlated intraocular pressure (IOP) and corneal-compensated IOP (r = 0.68; P < 0.001) and between Goldmann-correlated IOP and Goldmann applanation tonometry (r = 0.88; P < 0.001). CONCLUSIONS: Gender and advancing age may influence corneal biomechanical properties. In our population, CH decreased with aging, and men demonstrated a higher CH and CRF than women did. Further, CH, CRF, and CCT were significantly related.

ET-1 plasma levels, choroidal thickness and multifocal electroretinogram in retinitis pigmentosa.

AIM: To assess the relationship between both photoreceptor function and choroidal thickness and endothelin-1 (ET-1) plasma levels in patients with early stage retinitis pigmentosa (RP). MAIN METHODS: We compared 24 RP patients (14 males and 10 females), 25 to 42 years of age (mean age: 34±7 years) with 24 healthy controls (12 males and 12 females) aged between 28 and 45 years (mean 36±6.8 years). All patients underwent visual field test, electroretinogram and multifocal-electroretinogram and choroidal thickness measurement by using spectral domain optical coherence tomography. KEY FINDINGS: RP patients had a visual acuity of 0.95, a mean defect of the visual field of -7.90±1.75 dB, a pattern standard deviation index of 6.09±4.22 dB and a b-wave ERG amplitude of 45.08±8.24 µV. Notably RP subjects showed significantly increased ET-1 plasma levels and reduced choroidal thickness compared with controls: respectively, 2.143±0.258 pg/ml vs. 1.219±0.236 pg/ml; p<0.002 and 226.75±76.37 µm vs. 303.9±39.87 µm; p<0.03. Spearman's correlation test highlighted that the increase of ET-1 plasma levels was related with the decrease of choroidal thickness (r=-0.702; p<0.023) and the increase of implicit time in both ring 2 (r=-0.669; p<0.034) and ring 3 (r=-0.883; p<0.007) of mfERG. SIGNIFICANCE: Increased ET-1 plasma levels may play a key role in the impairment of retinal and choroidal blood flow due to the vasoconstriction induced by ET-1. This could lead to worsening of the abiotrophic process of the macular photoreceptors.

Subtenon injection of natural leukocyte interferon α-2a in diabetic macular edema: a case report.

BACKGROUND: To report the effect of subtenon injections of natural leukocyte interferon α-2a (IFNα) on best corrected visual acuity (BCVA) and central macular thickness (CMT) in a patient with diabetic macular edema (DME). CASE PRESENTATION: A 66-year-old man affected by DME, with glycated hemoglobin (HbA1c) at 6.9%, refractory to laser grid treatment and intravitreal injections of triamcinolone, was selected to receive a cycle of three subtenon injections/week of IFNα (1×106 IU/ml). BCVA and CMT, using spectral domain ocular coherence tomography (SD-OCT), were evaluated preoperatively and at 1 week, 1 month, 4 months, and 1 year postoperatively. BCVA and CMT were significantly improved at 1 week after the three injections (20/200 vs. 20/40 and 498 µm vs. 237 µm, respectively). BCVA remained stable during the 1-year follow-up. CMT was slightly increased, but was still lower than the baseline value (215 µm, 255 µm, and 299 µm during the follow-up visits). No adverse events were recorded, with the exception of mild subconjunctival hemorrhage at the injection site. CONCLUSIONS: IFNα, with its immunomodulatory, anti-proliferative and anti-angiogenic actions, was effective in improving BCVA and reducing CMT in refractory DME. Further randomized controlled studies are required to assess the effect of IFNα alone or in combination with other therapies for DME treatment.

Aqueous flare and choroidal thickness in patients with chronic hepatitis C virus infection: a pilot study.

PURPOSE: To investigate the status of the blood-aqueous barrier and to evaluate the subfoveal choroidal thickness (SCT) in patients with asymptomatic untreated chronic hepatitis C virus (HCV) infection without any anterior or posterior ocular involvement and to search for possible correlations. DESIGN: Observational case-control study. PARTICIPANTS AND CONTROLS: A total of 80 eyes of 20 HCV-positive patients (male-to-female ratio, 12:8; mean age, 46.9±7.23 years) and 20 healthy controls (male-to-female ratio, 10:10; mean age, 48.2±8.71 years) were examined. METHODS: Participants underwent a complete ophthalmologic examination. Aqueous flare was quantified objectively by using the noninvasive laser flare cell meter FC-500 (Kowa Company Ltd, Tokyo, Japan), whereas SCT was evaluated by using enhanced depth imaging optical coherence tomography (Spectralis OCT; Heidelberg Engineering GmbH, Heidelberg, Germany). A Wilcoxon rank-sum test was performed to compare ocular findings between HCV patients and controls, and correlations were assessed by using the Spearman rank test. MAIN OUTCOME MEASURES: Retinal and choroidal thickness and anterior chamber inflammation of HCV patients and healthy controls. RESULTS: Patients with HCV showed significantly higher aqueous flare values (8.37±2.25 photon counts/ms vs. 4.56±1.45 photon counts/ms; P<0.0001) and a significantly increased SCT (362.7±46.5 µm vs. 320.25±32.82 µm; P<0.0001) than healthy controls. Moreover, subjects with liver fibrosis had higher flare values than those with no significant hepatic fibrosis (9.62±1.99 photon counts/ms vs. 6.97±2.19 photon counts/ms; P = 0.0003) and thicker choroids (379.15±44.75 µm vs. 346.3±43.27 µm; P = 0.024). Statistical analysis revealed that there was a positive correlation between aqueous flare values and SCT in HCV patients (r = 0.69; P<0.0001) and between flare and the degree of liver fibrosis (r = 0.67; P = 0.0001). CONCLUSIONS: This study showed that impairment of the blood-aqueous barrier and thickened choroids are features of asymptomatic HCV patients, and that choroidal thickness increases as the degree of subclinical inflammation of the anterior chamber increases. Patients with significant liver fibrosis have the highest flare values and the thickest choroids.

Does pupil dilation influence subfoveal choroidal laser Doppler flowmetry?

PURPOSE: The aim of this study was to assess (i) whether pupil dilation with tropicamide influences subfoveal choroidal blood flow, as assessed by continuous laser Doppler flowmetry (LDF) and (ii) if this is the case, whether the effect is due to a haemodynamic response of the drug-induced dilation. METHODS: Following the instillation of one drop of 1% tropicamide in one eye of 18 healthy, nonsmoking volunteers (age 20-25 years), the subfoveal choroidal LDF parameters (Vel, Vol and ChBF) were recorded during 30 min, at 3-min intervals under two paradigms: through an artificial pupil (4 mm diameter) placed in front of the cornea (P1) and without this artificial pupil (P2). RESULTS: Tropicamide increased the pupil diameter from 3.3 ± 0.4 mm (mean ± SD) to 8.3 ± .4 mm. Full dilation was reached at ~24 min. During this period of time, linear regression analysis demonstrated that none of the LDF parameters varied significantly (p > 0.05), either under P1 or P2. Based on a group of 12 subjects, the smallest (%) change in the mean value of ChBF (ChBFm ) that would be detectable (sensitivity of the method, S) was found to be 2% for P1 and 6% for P2. The average coefficient of variation of ChBFm based on eight measurements during dilation was greater for P2 than for P1 by a factor of approximately 2. CONCLUSION: Tropicamide had no significant influence on the subfoveal choroidal LDF parameters measured by continuous LDF during pupil dilation. Furthermore, pupil dilation did not affect ChBFm by more than the calculated minimum percentage change of 6% detectable with our method.

Effectiveness of palmitoylethanolamide on endothelial dysfunction in ocular hypertensive patients: a randomized, placebo-controlled cross-over study.

PURPOSE: We assessed the effect of palmitoylethanolamide (PEA) on systemic endothelial function in ocular hypertensive patients (OH). METHODS: We enrolled in this randomized, double-blind, placebo-controlled, crossover single-center study 40 never-treated OH patients and 40 healthy age-matched controls. At baseline, each participant underwent endothelium-dependent flow-mediated vasodilation (FMD) measurement using a noninvasive high-resolution 2-dimensional ultrasonographic imaging of the brachial artery. OH patients were assigned randomly to receive either 300 mg PEA (Group A) or a matching placebo (Group B), twice a day for three months (T1). The first medication period was followed by a two-month washout period (T2), and then patients switched to PEA or placebo (depending on the first drug received) for another three months (T3). FMD evaluations were repeated at T1, T2, and T3. RESULTS: At baseline FMD values in OH patients and controls were 6.06 ± 0.60% vs. 10.85 ± 1.80%, respectively (P < 0.001). At T1, FMD and IOP of Group A were, respectively, 8.46 ± 1.09% vs. 6.08 ± 0.62% (P < 0.001, r = 0.96) and 22.18 ± 1.26 vs. 23.03 ± 0.88 mm Hg (P < 0.001). At T2, Group A had better FMD values than at baseline (6.59 ± 0.33% vs. 6.08 ± 0.62%, P < 0.05). At T3, subjects in Group B showed better FMD and IOP than at T2 (8.52 ± 1.07% vs. 6.05 ± 0.68%, P < 0.001, r = 0.97; and 22.43 ± 1.17 vs. 23.03 ± 0.83 mm Hg, P < 0.01, respectively). No side effects were observed. CONCLUSIONS: Three-month PEA intake reduced IOP and led to significantly improved FMD values in OH patients compared to placebo, by ameliorating peripheral endothelial function, and its positive effect lasted longer than the period of PEA consumption. No adverse events were recorded. (Controlled-trials.com number, ISRCTN72647928.).

Frequency doubling technology, optical coherence technology and pattern electroretinogram in ocular hypertension.

BACKGROUND: To assess which of three methods, namely, optical coherence tomography (OCT), pattern electroretinogram (PERG) or frequency-doubling technology (FDT), is the most sensitive and specific for detecting early glaucomatous damage in ocular hypertension (OH). METHODS: Fifty-two patients with OH (24 men and 28 women, mean age of 56 ± 9.6 years) with an intraocular pressure (IOP) > 21 mm Hg and fifty-two control patients (25 men and 27 women, mean age of 54.8 ± 10.4 years) with IOP < 21 mm Hg, were assessed. All the patients had normal visual acuity, normal optic disk and normal perimetric indices.All subjects underwent OCT, FDT and PERG. Data were analyzed with unpaired t-tests, Chi-square test and Receiver Operating Characteristic (ROC) curve analyses. RESULTS: In patients with OH, OCT showed retinal nerve fiber layer (RNFL) thinner than in control group in the superior quadrant (130.16 ± 10.02 vs 135.18 ± 9.27 µm, respectively; p < 0.011) and inferior quadrant (120.14 ± 11.0 vs 132.68 ± 8.03 µm; p < 0.001). FDT showed a significantly higher pattern standard deviation (PSD) (3.46 ± 1.48 vs 1.89 ± 0.7 dB; p < 0.001). With respect to PERG, only the amplitude showed significant differences (p < 0.044) between the two groups. ROC curve analysis revealed a sensitivity and specificity of 92% and 86%, respectively, for FDT-PSD (with an area under the ROC curve of 0.940), whereas with OCT, a sensitivity of 82% and a specificity of 74% was recorded in the inferior RNFL quadrant (with an area under the ROC curve of 0.806) finally with PERG amplitude we found a sensitivity of 52% and specificity of 77% (with an area under the ROC curve of 0.595). CONCLUSIONS: FDT is the most sensitive and specific method for detecting early glaucomatous damage in eyes with OH, and together with OCT, can be useful in identifying those patients who may develop glaucoma. TRIAL REGISTRATION: ISRCT number: ISRCTN70295497.

Endothelin-1 plasma levels and vascular endothelial dysfunction in primary open angle glaucoma.

AIMS: To assess the relationship between endothelial dysfunction, endothelin 1 (ET-1) plasma levels and subclinical inflammation in primary open angle glaucoma (POAG) patients. MAIN METHODS: We enrolled 40 POAG patients with progressive visual field damage, although well controlled intraocular pressure (IOP) and compared to age and sex matched healthxy subjects. Each patient underwent an ophthalmological examination, a standard achromatic perimetry (SAP), blood sampling to assess ET-1 plasma levels, an objective assessment of cellularity within the anterior chamber (FLARE) and measurement of flow mediated dilation (FMD) with high resolution 2-dimensional ultrasonographic imaging of the brachial artery. KEY FINDINGS: At baseline, POAG patients, compared to healthy controls, showed an increase of ET-1 plasma levels: 2.83 ± 0.28 pg/ml vs. 1.75 ± 0.25 pg/ml (p<0.001), lower FMD values 4.46 ± 1.28% vs. 13.18 ± 2.80% (p<0.001) and increased FLARE values 9.98 ± 0.97 photons/ms vs. 5.87 ± 0.64 photons/ms (p<0.001). A follow up after 1 year revealed a further increase of ET-1 plasma levels (to 3.68 ± 0.60; p<0.001) and decrease of FMD (3.52 ± 1.28; p>0.001). SIGNIFICANCE: The increase of ET-1 in POAG patients is related to vascular dysfunction (r=0.942; p=0.001) and vascular dysfunction is related to sub-clinical intraocular inflammation (r=0.968; p=0.001). Thus ET-1 and vascular dysfunction related to sub-clinical inflammation may play a key role in determining a progressive visual field damage in POAG patients who present a well-controlled IOP.

Multifocal electroretinogram and Optical Coherence tomography spectral-domain in arc welding macular injury: a case report.

BACKGROUND: the purpose of this study was to report a binocular photic retinal injury induced by plasma arc welding and the follow-up after treatment with vitamin supplements for a month. In our study, we used different diagnostic tools such as fluorescein angiography (FA), optical coherence tomography (OCT) and multifocal electroretinogram (mfERG). CASE PRESENTATION: in the first visit after five days from arc welding injury in the left eye (LE) the visual acuity was 0.9 and 1.0 in the right eye (RE). FA was normal in both eyes. OCT in the left eye showed normal profile and normal reflectivity and one month later, a hyperreflectivity appeared in the external limiting membrane (ELM). The mfERG signal in the LE was 102.30 nV/deg2 five days after the injury and 112.62 nV/deg2 after one month and in the RE respectively 142.70 nV/deg2 and 159.46 nV/deg2. CONCLUSIONS: in cases of retinal photo injury it is important for the ophthalmologist to evaluate tests such as OCT and the mfERG in the diagnosis and follow-up of the patient because the recovery of visual acuity cannot exclude the persistence of phototoxic damage charged to the complex inner-outer segment of photoreceptors.

Secondary IOL Implantation without Capsular Support: A Laser Flare Cell Meter Study.

Phacoemulsification and the contemporary implantation of intraocular lens (IOL) within the capsular bag represent the standard of care in cataract surgery, but sometimes a primary IOL implant is not possible due to intraoperative complications or preexisting conditions so that a secondary implantation of IOL within the anterior or posterior chamber is necessary. The aim of our study was to assess the degree of inflammation due to a secondary implant of claw lenses, angle-supported IOLs, and scleral-fixated IOLs by means of an objective, repeatable, and noninvasive device, the laser flare cell meter, which evaluates aqueous flare and cells within the anterior chamber in vivo and to show the contribution of the single IOLs to the genesis of inflammation.

ET-1 plasma levels and ocular blood flow in retinitis pigmentosa.

Retinitis pigmentosa (RP) is an inherited retinal disorder clinically characterized by a pale, waxy optic nerve head, attenuated retinal blood vessels, and bone spicule pigment in the retina. Hemodynamic studies have demonstrated that RP is associated with a reduction in the retinal and choroidal blood flow. Retinal hemodynamic impairment is also present in early stages of RP, and various hypotheses have been advanced as to the cause. The authors studied 20 patients, 12 males and 8 females, aged 26-42 years (mean 35.1 years) and affected by simplex RP. The patients had a visual acuity of 0.9 +/- 0.1, visual field mean defect of -6.52 +/- 3.58 dB, and b-wave electroretinogram amplitude of 260.08 +/- 8.24 microV. An increase in plasma levels of endothelin-1 (ET-1) was found: 1.910 +/- 0.317 pg/mL versus 1.180 +/- 0.210 pg/mL in non-RP controls (p < 0.02). Moreover both an ocular and systemic vascular impairment was detected by means of color Doppler imaging and laser Doppler flowmetry performed during a cold pressor test. We found a correlation between the increase of ET-1 plasma levels in RP and the decrease of peak systolic velocity in the ophthalmic artery (p < 0.03) and in the posterior ciliary arteries (p < 0.006). It is thought that an increase of ET-1 and retinal oxygen levels in RP could lead to vasoconstriction and a decrease of the retinal blood flow, worsening the abiotrophic process.

Corneoscleral graft in Mooren's ulcer: a case report.

INTRODUCTION: Mooren's ulcer is a rare disorder of unknown etiology that is refractory to treatment. It can affect not just the cornea but also the scleral tissue and can involve both eyes. CASE PRESENTATION: We report a case of a 74-year-old man with a history of bilateral and malignant Mooren's ulcer. The patient had undergone an exenteratio bulbi of the left eye because of the perforation of a Mooren's corneal ulcer. The perforated Mooren's corneal ulcer also presented in the right eye and involved the adjacent scleral tissue. It was decided to perform a corneal-scleral graft to preserve the anatomical integrity of the eye. CONCLUSION: This report highlights how a corneal-scleral graft followed by systemic and local immunosuppressive treatment should be considered in monocular patients with malignant Mooren's ulcer where there is serious damage to the corneal and scleral tissue.

Matrix metalloproteinases and their tissue inhibitors after selective laser trabeculoplasty in pseudoexfoliative secondary glaucoma.

BACKGROUND: The aim of this study was to assess changes in metalloproteinases (MMP-2) and tissue inhibitor of metalloproteinases (TIMP-2) following selective laser trabeculoplasty (SLT) in patients with pseudoexfoliative glaucoma (PEXG). METHODS: We enrolled 15 patients with PEXG and cataracts (PEXG-C group) and good intraocular pressure (IOP) controlled with beta-blockers and dorzolamide eye drops who were treated by cataract phacoemulsification and 15 patients with pseudoexfoliative glaucoma (PEXG-SLT group). The PEXG-SLT patients underwent a trabeculectomy for uncontrolled IOP in the eye that showed increased IOP despite the maximum drug treatment with beta-blockers and dorzolamide eye drops and after ineffective selective laser trabeculoplasty (SLT). The control group consisted of 15 subjects with cataracts. Aqueous humor was aspirated during surgery from patients with PEXG-C, PEXG-SLT and from matched control patients with cataracts during cataract surgery or trabeculectomy. The concentrations of MMP-2 and TIMP-2 in the aqueous humor were assessed with commercially available ELISA kits. RESULTS: In PEXG-SLT group in the first 10 days after SLT treatment a significant reduction in IOP was observed: 25.8 +/- 1.9 vs 18.1.0 +/- 1.4 mm/Hg (p < 0.001), but after a mean time of 31.5 +/- 7.6 days IOP increased and returned to pretreatment levels: 25.4 +/- 1.6 mm/Hg (p < 0.591). Therefore a trabeculectomy was considered necessary.The MMP-2 in PEXG-C was 57.77 +/- 9.25 microg/ml and in PEXG-SLT was 58.52 +/- 9.66 microg/ml (p < 0.066). TIMP-2 was 105.19 +/- 28.53 microg/ml in PEXG-C and 105.96 +/- 27.65 microg/ml in PEXG-SLT (p < 0.202). The MMP-2/TIMP-2 ratio in the normal subjects was 1.11 +/- 0.44. This ratio increase to 1.88 +/- 0.65 in PEXG-C (p < 0.001) and to 1.87 +/- 0.64 in PEXG-SLT (p < 0.001). There was no statistically significant difference between the PEXG-C and PEXG-SLT ratios (p < 0.671). CONCLUSION: This case series suggest that IOP elevation after SLT can be a serious adverse event in some PEXG patients. The IOP increase in these cases would be correlated to the failure to decrease the TIMP-2/MMP-2 ratio. TRIAL REGISTRATION: Current Controlled Trials ISRCTN79745214.