Influence of disc area on retinal nerve fiber layer thickness measurement by spectral domain optical coherence tomography

Background:

To examine the effect of optic disc area on peripapillary RNFLT (retinal nerve fiber layer thickness) measurement at circle diameter of 3.4 mm around optic nerve head using spectral OCT/SLO (Optical coherence tomography/scanning laser ophthalmoscope).

Materials and Methods:

In this prospective, cross sectional study, one hundred and two eyes of 102 normal subjects underwent RNFLT and disc area measurement using spectral OCT/SLO. Based on disc area, subjects were divided into three groups i.e., <3 mm² (32 eyes), 3-4 mm² (36 eyes) and >4 mm² (34 eyes). The effect of disc area on RNFLT parameters was analyzed using linear regression analysis.

Results:

The mean and quadrant RNFLT did not show significant correlation with disc area in subjects with disc area of <4 mm², however in eyes with disc area >4 mm², average RNFLT, superior and temporal quadrant RNFLT showed negative correlation with disc area, which was statistically significant (P = 0.004, P = 0.005 and P = 0.002, respectively)

Conclusion:

In healthy eyes of disc area <4 mm², disc size does not appear to affect peripapillary RNFLT measurement by spectral OCT/SLO. Average, superior and temporal quadrant RNFLT measurements were inversely proportional to disc area in eyes with disc area >4 mm². Hence, RNFLT measurement by OCT in eyes with optic disc area of >4 mm² should be interpreted carefully.     

Temporary morphological changes in plus disease induced during contact digital imaging

Objective

To compare and quantify the retinal vascular changes induced by non-intentional pressure contact by digital handheld camera during retinopathy of prematurity (ROP) imaging by means of a computer-based image analysis system, Retinal Image multiScale Analysis.

Methods

A set of 10 wide-angle retinal pairs of photographs per patient, who underwent routine ROP examinations, was measured. Vascular trees were matched between ‘compression artifact'' (absence of the vascular column at the optic nerve) and ‘not compression artifact'' conditions. Parameters were analyzed using a two-level linear model for each individual parameter for arterioles and venules separately: integrated curvature (IC), diameter (d), and tortuosity index (TI).

Results

Images affected with compression artifact showed significant vascular d (P<0.01) changes in both arteries and veins, as well as in artery IC (P<0.05). Vascular TI remained unchanged in both groups.

Conclusions

Non-adverted corneal pressure with the RetCam lens could compress and decrease intra-arterial diameter or even collapse retinal vessels. Careful attention to technique is essential to avoid absence of the arterial blood column at the optic nerve head that is indicative of increased pressure during imaging.     

Spectral domain optical coherence tomography for early detection of retinal alterations in patients using hydroxychloroquine

Objective:

To determine whether early toxic effects from hydroxychloroquine (HCQ) could be detected by spectral-domain optical coherence tomography (SD-OCT) before symtomatic visual loss occured.

Materials and Methods:

Fifteen subjects with a history of the chronic use of hydroxychloroquine monotherapy for less than five years without fundus changes (group 1) and 15 visually normal healthy subjects (group 2) were enrolled in this study. All participants underwent systemic and ocular examination, visual field testing, and macular scan imaging using SD-OCT.

Results:

There were no significant differences in sex and ages between the groups (P > 0.05). Mean duration of HCQ usage in group 1 was 2.5 ± 1.34 (range:1-5) years. Visual field testing with central 10-2 threshold program was normal in all subjects. Inner retinal thickness in parafoveal and perifoveal area were found to be significantly lower in group 1 compared to group 2 (P < 0.01 for perifoveal, P < 0.05 for parafoveal retinal measurements). However, significant thinning was demonstrated only in full retinal thickness of perifoveal area in group 1 compared to group 2 (P: 0.013). Parafoveal and perifoveal inner retinal thickness measurements of inferior quadrants were significantly reduced in group 1 compared to group 2 (P < 0.01).

Conclusion:

Significant thinning of inner retinal layer especially in parafoveal and perifoveal areas in the absence of clinical fundus changes was observed in our study. We consider that SD-OCT may determine when inner retinal thinning starts in these patients and may contribute a quantitative approach to the early diagnosis and progression of retinal changes.     

Orbital Doppler evaluation of blood flow velocities in optic neuritis

Purpose

To evaluate orbital blood flow velocities and optic nerve diameter with Doppler and gray-scale sonography in patients with acute unilateral optic neuritis (ON).

Methods

Orbital Doppler and gray-scale sonography was performed in 46 eyes of 23 patients aged 19- to 47-years with acute unilateral ON. ON was diagnosed by an ophthalmologist on the basis of clinical presentation, presence of decreased visual acuity and assessment of visual evoked potentials. The peak systolic velocity (PSV) and end-diastolic velocity (EDV), as well as the resistance index (RI) and pulsatile index (PI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary arteries (PCAs) and optic nerve diameter were measured in both eyes. We compared results from affected and unaffected eyes using the paired t-test. The area under the receiver operating characteristic (ROC) curves was used to assess the diagnosis of ON based on measured blood flow parameters of the OA, CRA and PCAs and optic nerve diameter.

Results

The mean (standard deviation) optic nerve diameter in eyes with ON was 4.1 (0.8) mm, which was significantly larger than the 3.0 (0.4) mm diameter measured in unaffected control eyes (p < 0.001). There were no differences in average PSV, EDV, RI, or PI of the OA and CRA between affected and unaffected eyes (p > 0.05). The mean RI in the PCAs was slightly lower in the eyes with ON than in the contralateral eyes (0.60 vs. 0.64, p < 0.05). The area under the ROC curves indicated that optic nerve diameter was the best parameter for the diagnosis of ON.

Conclusions

Optic nerve diameter was related to ON, but orbital blood flow parameters were not.     

Heparan sulfate regulates intraretinal axon pathfinding by retinal ganglion cells

PURPOSE. Heparan sulfate (HS) is abundantly expressed in the developing neural retina; however, its role in the intraretinal axon guidance of retinal ganglion cells (RGCs) remains unclear. In this study, the authors examined whether HS was essential for the axon guidance of RGCs toward the optic nerve head. METHODS. The authors conditionally ablated the gene encoding the exostosin-1 (Ext1) enzyme, using the dickkopf homolog 3 (Dkk3)-Cre transgene, which disrupted HS expression in the mouse retina during directed pathfinding by RGC axons toward the optic nerve head. In situ hybridization, immunohistochemistry, DiI tracing, binding assay, and retinal explant assays were performed to evaluate the phenotypes of the mutants and the roles of HS in intraretinal axon guidance. RESULTS. Despite no gross abnormality in RGC distribution, the mutant RGC axons exhibited severe intraretinal guidance errors, including optic nerve hypoplasia, ectopic axon penetration through the full thickness of the neural retina and into the subretinal space, and disturbance of the centrifugal projection of RGC axons toward the optic nerve head. These abnormal phenotypes shared similarities with the RGC axon misguidance caused by mutations of genes encoding Netrin-1 and Slit-1/2. Explant assays revealed that the mutant RGCs exhibited disturbed Netrin-1-dependent axon outgrowth and Slit-2-dependent repulsion. CONCLUSIONS. The present study demonstrated that RGC axon projection toward the optic nerve head requires the expression of HS in the neural retina, suggesting that HS in the retina functions as an essential modulator of Netrin-1 and Slit-mediated intraretinal RGC axon guidance.     

Spectral domain optical coherence tomography morphology in optic disc pit associated maculopathy

Purpose:

Our purpose was to study the clinical manifestation and course of optic pit maculopathy using Spectral Domain Optical Coherence Tomography (SD- OCT) images.

Materials and Methods:

We used SD-OCT to examine 20 eyes of 19 patients with a macular detachment in combination with an optic.

Results:

We observed five different fovea appearances in regard to fluid localization. In five eyes, we recorded changes in the fluid distribution with SD-OCT. In 17/20 eyes, we noted a communication between the perineural and subretinal and/or intraretinal space at the margin of the optic disc.

Conclusion:

3-dimensional SD-OCT (3D-SDOCT) scans revealed a three-fold connection, between subretinal and intraretinal space, perineural space, and the vitreous cavity. Therefore, we suppose that intraretinal or subretinal fluid in optic pit maculopathy may have both a vitreous and cerebrospinal origin. A membrane, covering the optic nerve was noted in 14 cases. Even if it seems intact in some B-scans, it is not complete in others several micrometers apart. Additionally, we observed fluid accumulation below the margin of the optic disc and hyperreflective porous tissue in the optic disc excavation. Those findings do not influence the course of maculopathy.     

Diffusion tensor imaging of optic nerve and optic radiation in primary chronic angle-closure glaucoma using 3T magnetic resonance imaging

AIM: To evaluate the value of quantitative diffusion tensor imaging (DTI) in assessing the axonal and myelin damage of the optic nerves and optic radiations in patients with chronic primary angle-closure glaucoma (PACG) by using high-field magnetic resonance (MR) imaging (3T).METHODS:Twenty patients with bilateral chronic PACG and twenty age- and sex matched disease-free control subjects were enrolled. Conventional MRI and DTI were performed on all subjects using 3T MR scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivities (AD) and radial diffusivities (RD) of each optic nerve and each optic radiation were measured by using post-processing software of DTI studio 2.3, and then compared between left eyes and right eyes and between patients group and control group. The paired-sample t- test were used．RESULTS: There was no abnormality in the shape and signal intensity of the optic nerves and optic radiations in patients group and control group on the conventional MRI. No significant differences were observed in the FA, MD, AD and RD between the right and left optic nerves and optic radiations within patients group and control group (P＞0.05). The optic nerves and optic radiations of patients with chronic PACG, as compared with control subjects, had significantly higher MD, AD, RD and significantly lower FA (P<0.05).CONCLUSION:The diffusivity of optic nerves and optic radiations in chronic PACG group showed abnormal and diffusivity parameters could be used markers of axonal and myelin injury in glaucoma.     

Correlation of visual field defects and optical coherence tomography finding in migraine patients

Aim of work

The aim of our work was to detect any structural or functional visual defects during and in between the attacks in patients with migraine.

Patient and methods

Sixty patients with migraine as well as sixty age and sex matched controls were included. All cases were subjected to full ophthalmological examination. Cases with any previously known optic nerve abnormalities or with history of increased intraocular pressure were excluded from this study. A full threshold 24-2 automated perimetry as well as optical coherence tomography (OCT) were performed for retinal nerve fiber layer (RNFL) thickness. Correlations between results of study group with migraine and controls were analyzed and recorded.

Results

There was a statistically significant difference between the patients with migraine and the controls in visual field analysis which was (P < 0.05) for generalized visual field deficits and (P < 0.001) for localized visual field deficits during the attack with no statistically significant difference in visual field in between the attacks (P > 0.05). OCT RNFL thickness had no statistically significant difference between migraine and control groups (P > 0.05).

Conclusion

Migraine can cause functional ocular disorder without any structural abnormalities.     

Clinicopathological correlation of parapapillary atrophy in monkeys with experimental glaucoma and temporary central retinal artery occlusion

Objective:

To investigate the clinicopathological correlation of parapapillary atrophy.

Materials and Methods:

The study included 16 eyes of rhesus monkeys (Macaca mulatta) – 4 eyes with experimental glaucoma, 11 eyes after experimental temporary occlusion of the central retinal artery, and 1 normal eye. On histological sections, we measured zones with different histological characteristics. On fundus photographs, alpha zone and beta zone of parapapillary atrophy were measured and correlated with the histological data.

Results:

The size of the clinical alpha zone of parapapillary atrophy was significantly correlated with the size of the histological region with irregularities of the retinal pigment epithelium (P = 0.05; correlation coefficient r = 0.49) and with the size of the histological region with a decreased density of retinal photoreceptors (P = 0.01; r = 0.60). The size of clinical beta zone of parapapillary atrophy significantly correlated with the size of the histological region with complete loss of the retinal pigment epithelium (P <0.001; r = 0.91), with the size of the histological zone with a complete loss of photoreceptors (P <0.001; r = 0.81), and with the size of the histological zone with a closed choriocapillaris (P <0.001; r = 0.89).

Conclusions:

The clinically seen alpha zone of parapapillary atrophy correlates with histological parapapillary irregularities of the retinal pigment epithelium and decreased density of retinal photoreceptors. The clinically seen beta zone of parapapillary atrophy correlates with histological complete loss of the retinal pigment epithelium and of the photoreceptors, and a closure of the choriocapillaris.     

Retinal sensitivity in healthy Indians using microperimeter

Aims:

To establish the retinal sensitivity values in healthy Indians using microperimeter.

Materials and Methods:

In this prospective study, 144 healthy volunteers were included. All the participants underwent a comprehensive ophthalmic examination including contrast sensitivity. Microperimetry was performed in the central 20° of the macula using 76 stimulus points to assess the retinal sensitivity, and the fixation characteristics in the study population were assessed.

Results:

The mean age of the study sample was 43.08 ± 10.85 years (range: 25-69). Mean retinal sensitivity was 18.26 ± 0.99 dB. Males had significantly increased retinal sensitivity (18.34 vs. 18.17 dB, P = 0.03). The linear regression analysis revealed a 0.04 dB per year age-related decline in mean retinal sensitivity. Contrast sensitivity was significantly correlated with the mean retinal sensitivity (r = 0.432, P < 0.001). Fixation stability in the central 2° and 4° were 69% and 89%, respectively.

Conclusion:

Microperimeter is an ideal tool to assess the retinal sensitivity and the fixation behavior. These normative values could help in drawing a meaningful conclusion in various retinal pathologies.     

The impact of octreotide in experimental proliferative vitreoretinopathy

Aims:

This study aims to investigate the effects of intravitreal octreotide on the growth factors, which have significant roles in the pathogenesis of proliferative vitreoretinopathy (PVR).

Settings and Design:

An experimental trial.

Materials and Methods:

21 guinea pigs were randomly assigned to form 3 groups each including 7 animals. In group 1 (the control group), 0.2 ml saline solution was applied intravitreally in a location of 1.5 mm behind the limbus. In group 2 (the sham group), 0.07 IU dispase in 0.1 ml and 0.1 ml saline solution were applied via the same route. The guinea pigs in group 3 (the treatment group) were applied 0.07 IU dispase in 0.1 ml and 1 mg octreotide in 0.1 ml via the same route. Octreotide injection was applied twice during the period of 10 weeks of the experiment. At the end of the 10 weeks, eyes were enucleated and retinal homogenates were prepared. The platelet derivated growth factor (PDGF), insulin-like growth factor (IGF 1) and transforming growth factor (TGF ß) levels in homogenized retina tissue were measured by Enzyme Linked-Immuno-Sorbent Assay (ELISA) method.

Statistical Analysis Used:

Kruskal-Wallis variance analysis and Mann-Whitney U test.

Results:

In the treatment group, a significant decrease was observed in retinal PDGF levels (P < 0.01) while decreases in TGF ß and IGF 1 levels were not found to be significant (P > 0.05).

Conclusions:

Intravitreally applied octreotide at a dose of 1 mg has a highly strong effect on PDGF. This study suggests that intravitreal octreotide may suppress PVR development and that octreotide may merit investigation for PVR prophylaxis.     

Identification of glaucomatous optic nerve head changes in Indian donor eyes without clinical history

Purpose:

The purpose of this study is to develop methods to identify glaucoma by examining the optic nerve head (ONH) of donor''s eyes when information on the preexisting ocular disease is unavailable.

Materials and Methods:

The ONH of the donor''s eyes was evaluated under a stereomicroscope for the cup-disc ratio (CDR) and focal retinal rim thinning. The vertical diameter of the cup and disc was also measured using a precalibrated eyepiece micrometer. The suspect eyes were subjected to histological analysis to confirm the presence of specific glaucomatous changes.

Results:

A total of 202 eyes from 119 donors (68 males and 51 females, aged 42–96) were evaluated for glaucoma. Among them, 190 (94%) eyes showing vertical CDR in the of 0.0–0.6 range were considered nonglaucomatous and the remaining eyes with >0.6 as glaucoma suspect. The calculated mean CDR of the two groups (0.3 ± 0.16, 0.62 ± 0.27) was highly significant (P = 0.0003). Of 12 eyes suspected of glaucoma, 7 eyes from 5 donors showed specific glaucomatous changes by histology. The prevalence of glaucoma was 4.2% among the donors studied.

Conclusions:

A simple method of screening fresh donor eyes for selecting those with glaucoma features using CDR and histological analysis was reported. This method helps to obtain biologically active human ocular tissue for glaucoma research on gene expression, ultrastructural/proteome changes, and outflow mechanism.     

Mean retinal ganglion cell axon diameter varies with location in the human retina

Purpose

We examined retinal ganglion cell (RGC) axon diameters within the human retinal nerve fibre layer in order to provide information about the possible effects of axonal stimulation when a retinal prosthesis includes the nonfoveal regions.

Methods

Five pairs of eyes were obtained from donors aged from 48 to 84?years. Fixation delay ranged from 5 to 22?h. Tissue was processed for electron microscopy.

Results

Inferior and/or nasal RGC axons were on average larger than superior and/or temporal axons. The inferior retina contained some very large axons. Foveal axons were on average smaller than nonfoveal axons and had a size distribution that suggested different size groupings not seen in other samples. Peripheral versus central axons within the superior and inferior nasal retinal samples were compared; peripheral axons were significantly larger, unlike the inferior temporal samples or the samples nasal to the optic disc.

Conclusions

Stimulus-current thresholds will change as a retinal prosthesis increases in size and encroaches on the nonfoveal axons. These changes can be anticipated based on mean axon diameter. Knowing in advance the possible outcome of electrical stimulation of the axonal population may help refine prosthetic procedures and patient training.     

Chorio-retinal thickness measurements in patients with acromegaly

Purpose

To compare choroidal, foveal, and peripapillary retinal thickness between patients with acromegaly and healthy adults.

Methods

This prospective, cross-sectional, and comparative study included 30 patients with acromegaly (study group) and 30 healthy subjects (control group). The subfoveal choroidal thickness (SFCT), foveal thickness, and peripapillary retinal nerve fibre layer thickness were measured with spectral domain optical coherence tomography.

Results

The mean SFCT in the study group and in the control eyes was 374.4±98.1 and 308.6±77.3 μm, respectively (P<0.001). The mean thinnest foveal thickness value was 233.2±22.4 μm in the acromegaly group and 222.8±13.9 μm in the control group (P=0.003). The mean peripapillary retinal nerve fibre layer thickness did not differ significantly between the groups (P=0.34).

Conclusion

The SFCT and foveal thickness were significantly higher in patients with acromegaly, whereas peripapillary retinal nerve fibre layer thickness was similar between the groups.     

Short-term changes in the optic nerve head and visual field after trabeculectomy

Aims or Purpose

To evaluate short-term changes in optic nerve head topography and visual field induced by surgical reduction of intraocular pressure.

Methods

A prospective study was performed on 56 eyes of 56 patients with uncontrolled primary open-angle glaucoma despite maximum medical therapy, which underwent trabeculectomy. Optic nerve head evaluations by means of Heidelberg Retina Tomograph, and visual field tests were performed pre-operatively, and at 3 and 6 months after surgery. Differences in intraocular pressure, visual field indices, and Heidelberg Retina Tomograph parameters were evaluated with the t-test for paired data. A linear regression model was calculated to analyze the relationship between intraocular pressure reduction and visual field changes, and optic nerve head changes.

Results

Mean intraocular pressure decreased from 24.4±5.0 mm Hg to 12.1±3.1 mm Hg (month 3, P<0.001), and 10.6±2.8 mm Hg (month 6, P<0.001) after trabeculectomy. Mean retinal nerve fiber layer thickness (baseline, 0.19±0.034; month 3, 0.24±0.039, P=0.05; month 6, 0.21±0.037, P=0.05) showed a statistical significant change compared with baseline values.

Conclusions

In this 6-months study, a significant increase in retinal nerve fiber layer thickness was detected after glaucoma filtration surgery.     

Visual outcomes after carotid reconstructive surgery for ocular ischemia

Aims

This study aimed to determine the influence of carotid artery surgery on ocular functions and ocular blood flow in patients with ocular ischaemic syndrome (OIS) in the late postoperative period.

Methods

One hundred and eighty patients with OIS were operated on; 104 of them suffered from acute forms of the ischaemic disease and 76 patients had chronic forms of ocular ischaemia. Before surgery and in the course of 6 months and 12 months afterwards, all the patients were examined. Visual acuity, electrophysiological investigations (the threshold of electrical sensitivity (TES) and the level of liability of optic nerve (LON)) and blood flow in orbital vessels were assessed.

Results

After surgery visual acuity increased in patients with the acute forms of OIS (P<0.05). TES and LON also improved (P<0.01). Mean indices of blood-flow velocities in the ophthalmic artery, the central retinal artery and the posterior ciliary arteries increased at 6 and 12 months after surgery (P<0.05). There was ocular blood flow acceleration and decrease of vasoresistance in orbital arteries in both groups of patients.

Conclusions

Carotid artery surgery effectively improved ocular blood flow in patients with acute and chronic forms of OIS in the late post operative period.     

Color vision versus pattern visual evoked potentials in the assessment of subclinical optic pathway involvement in multiple sclerosis

Background:

Optic pathway involvement in multiple sclerosis is frequently the initial sign in the disease process. In most clinical applications, pattern visual evoked potential (PVEP) is used in the assessment of optic pathway involvement.

Objective:

To question the value of PVEP against color vision assessment in the diagnosis of subclinical optic pathway involvement.

Materials and Methods:

This prospective, cross-sectional study included 20 multiple sclerosis patients without a history of optic neuritis, and 20 healthy control subjects. Farnsworth-Munsell (FM) 100-Hue testing and PVEPs to 60-min arc and 15-min arc checks by using Roland-Consult RetiScan^® system were performed. P₁₀₀ amplitude, P₁₀₀ latency in PVEP and total error scores (TES) in FM 100-Hue test were assessed.

Results:

Expanded Disability Status Scale score and the time from diagnosis were 2.21 ± 2.53 (ranging from 0 to 7) and 4.1 ± 4.4 years. MS group showed significantly delayed P₁₀₀ latency for both checks (P < 0.001). Similarly, MS patients had significantly increased total error scores (TES) in FM-100 Hue (P < 0.001). The correlations between TESs and PVEP amplitudes / latencies were insignificant for both checks (P > 0.05 for all). 14 MS patients (70%) had an increased TESs in FM-100 Hue, 11 (55%) MS patients had delayed P₁₀₀ latency and 9 (45%) had reduced P₁₀₀ amplitude. The areas under the ROC curves were 0.944 for FM-100 Hue test, 0.753 for P₁₀₀ latency, and 0.173 for P₁₀₀ amplitude.

Conclusions:

Color vision testing seems to be more sensitive than PVEP in detecting subclinical visual pathway involvement in MS.     

Morphological Consequences of Myelination in the Human Retina

Intraretinal myelination of ganglion cell axons occurs in about 1% of humans and when observed ophthalmoscopically, appears as a white or opaque patch within the fiber layer. Previous studies of myelinated retinal tissue have largely been conducted at the light microscopic level. Three retinae with intraretinal myelination and one normal retina were obtained post-mortem and prepared for electron microscopy. The present study showed that myelinated patches in the human retina contained a mixture of unmyelinated and myelinated axons. Within this population of myelinated axons were structures which were abnormal and there were obvious signs of axonal and myelin sheath degeneration within the myelinated patches. Outside these myelin patches the retina appeared normal without signs of degeneration indicating that post-mortem degeneration prior to fixation could not account for all of the degenerative changes observed. The lack of significant numbers of macrophages and lymphocytes indicated that there was no concomitant inflammatory process within the myelin patches. The myelination present within these eyes appeared to be due to the anomalous location of oligodendrocytes. Both unmyelinated and myelinated axons had larger diameters than axons measured within normal areas of the retina or those within the optic nerve.     

Improvement of central retinal sensitivity six months after topical isopropyl unoprostone in patients with retinitis pigmentosa

Aims:

Isopropyl unoprostone (IU), a maxi-K channel activator, is used topically to treat glaucoma, and has been reported to have neuroprotective effects on retinal neurons in vitro and in vivo. The purpose of this non-comparative pilot study was to determine whether topical IU will alter the sensitivity of the central retina in patients with retinitis pigmentosa (RP).

Settings and Design:

Non-comparative pilot study.

Materials and Methods:

IU was given topically twice a day for 6 months to both eyes of 30 patients with typical RP. The visual acuity was measured with a Japanese Snellen chart, and the mean retinal sensitivities were obtained by fundus-related microperimetry (MP-1). The mean deviation (MD) of the visual field was determined with a Humphrey field analyzer (HFA). All measurements were made before and 6 months after the treatment.

Statistical Analysis Used:

Wilcoxon and the Mann-Whitney U tests (SPSS, SPSS Inc., Chicago, IL).

Results:

After the treatment, the mean retinal sensitivity within the central 2° and 10° improved significantly from 12.3 ± 4.8 dB to 14.7 ± 5.5 dB (P = 0.001) and from 9.1 ± 5.4 dB to 11.0 ± 6.2 dB (P = 0.001), respectively.

Conclusions:

These short-term results suggest topical IU can improve the central retinal sensitivity in RP patients. It will be necessary to examine longer treatment periods in a controlled study to determine the effectiveness of topical IU in RP patients.