Identification of genes involved in glaucoma pathogenesis using combined network analysis and empirical studies.

Glaucoma is a leading cause of blindness. We aimed in this study to identify genes that may make subtle and cumulative contributions to glaucoma pathogenesis. To this end, we identified molecular interactions and pathways that include transcription factors (TFs) FOXC1, PITX2, PAX6 and NFKB1 and various microRNAs including miR-204 known to have relevance to trabecular meshwork (TM) functions and/or glaucoma. TM tissue is involved in glaucoma pathogenesis. In-house microarray transcriptome results and data sources were used to identify target genes of the regulatory molecules. Bioinformatics analyses were done to filter TM and glaucoma relevant genes. These were submitted to network-creating softwares to define interactions, pathways and a network that would include the genes. The network was stringently scrutinized and minimized, then expanded by addition of microarray data and data on TF and microRNA-binding sites. Selected features of the network were confirmed by empirical studies such as dual luciferase assays, real-time PCR and western blot experiments and apoptosis assays. MYOC, WDR36, LTPBP2, RHOA, CYP1B1, OPA1, SPARC, MEIS2, PLEKHG5, RGS5, BBS5, ALDH1A1, NOMO2, CXCL6, FMNL2, ADAMTS5, CLOCK and DKK1 were among the genes included in the final network. Pathways identified included those that affect ECM properties, IOP, ciliary body functions, retinal ganglion cell viability, apoptosis, focal adhesion and oxidative stress response. The identification of many genes potentially involved in glaucoma pathology is consistent with its being a complex disease. The inclusion of several known glaucoma-related genes validates the approach used.

COL18A1 is a candidate eye iridocorneal angle-closure gene in humans.

Primary angle-closure glaucoma (PACG) is a common form of glaucoma in the Far East. Its defining feature is iridocorneal angle closure. In addition to PACG, indications of angle closure are included in the diagnostic criteria of related conditions primary angle-closure suspect (PACS) and primary angle closure (PAC). To the best of our knowledge, a causative gene for iridocorneal angle closure in humans has not been identified. This study aimed to identify the genetic cause of iridocorneal angle closure in a pedigree with at least 10 individuals diagnosed with PACS, PAC or PACG. Results of linkage analysis, segregation analysis of 44 novel variations, whole exome sequencing of 10 individuals, screenings of controls and bioinformatics predictions identified a mutation in COL18A1 that encodes collagen type XVIII as the most likely cause of angle closure in the pedigree. The role of COL18A1 in the etiology of Knobloch syndrome (KS) that is consistently accompanied by optic anomalies, available functional data on the encoded protein and the recognized role of collagens and the extracellular matrix in glaucoma pathogenesis supported the proposed role of the COL18A1 mutation in the pedigree. Subsequent identification of other COL18A1 mutations in PACS affected individuals of two unrelated families further supported that COL18A1 may affect angle closure. These PACS individuals were parents and grandparents of KS-affected children. In conclusion, a gene that affects angle closure in humans, a critical feature of PACG, has been identified. The findings also reinforce the importance of collagens in eye features and functions.

Congenital Four Eyelid Ectropion Associated With Clefting Anomaly.

An infant with congenital 4 eyelid ectropion associated with cleft lip and palate developed exposure keratopathy. He underwent skin grafting of the upper eyelids and lateral canthal reconstruction. Ectropion and signs of exposure keratopathy improved. Congenital eyelid ectropion is a rare disorder. Surgical repair can successfully correct the condition.

Trichloroacetic acid 10% injection for treatment of conjunctival inclusion cysts.

Purpose: To evaluate the effect of intra-lesional injection of Trichloroacetic acid (TCA) 10% in patients with conjunctival inclusion cysts.Methods: This prospective case series study included all patients with conjunctival inclusion cyst who were referred to our referral center from August 2016 to August 2018. All patients received TCA 10% injection into the conjunctival cyst, and outcomes of the intervention were evaluated at least 6 months later.Results: Ten patients with mean age of 24 ± 17.6 (range 6-65) years including three children received TCA 10% injection into the conjunctival cyst. We included 6 anophthalmic and 4 ophthalmic cases. All patients were treated successfully and no recurrence of the lesion was observed in any case. Mean follow up duration was 18.1 ± 8.3 (range 6-28) months.Conclusion: Intra-lesional injection of TCA 10% is a safe, simple, and effective treatment in patients with conjunctival inclusion cysts including ophthalmic cases and anophthalmic cases, both in adults and in children. This concentration may avoid ocular surface complications.

Peptide selected by phage display increases survival of SH-SY5Y neurons comparable to brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) is a well-known neuroprotectant and a potent therapeutic candidate for neurodegenerative diseases. However, there are several clinical concerns about its therapeutic applications. In the current study, we designed and developed BDNF-mimicking small peptides as an alternative to circumvent these problems. A phage-displayed peptide library was screened using BDNF receptor (neurotrophic tyrosine kinase receptor type2 [NTRK2]) and evaluated by ELISA. The peptide sequences showed similarity to loop2 of BDNF, they were recognized as discontinuous epitopes though. Interestingly, in silico molecular docking showed strong interactions between the peptide three-dimensional models and the surface residues of the NTRK2 protein at the IgC2 domain. A consensus peptide sequence was then synthesized to generate a mimetic construct (named as RNYK). The affinity binding and function of this construct was confirmed by testing against the native structure of NTRK2 in SH-SY5Y cells in vitro using flow-cytometry and MTT assays, respectively. RNYK at 5 ng/mL prevented neuronal degeneration of all- trans-retinoic acid-treated SH-SY5Y with equal efficacy to or even better than BDNF at 50 ng/mL.

Analysis of pattern electroretinogram signals of early primary open-angle glaucoma in discrete wavelet transform coefficients domain.

PURPOSE: To evaluate discrete wavelet transform coefficients and identify descriptors of pattern electroretinogram (PERG) waveforms in order to determine PERG characteristics for optimizing the diagnosis of early primary open-angle glaucoma (POAG). METHODS: Pattern electroretinogram was performed in 30 normal eyes and 30 eyes with primary open-angle glaucoma according to the ISCEV protocol. The check size was 0.8° and 16°, and the color was black/white in both groups. The results were analyzed in time domain (TD) and discrete wavelet transform (DWT) using the MATLAB software. The mean value, standard deviation, and relative energy of level 6 and 7 detail coefficients (d6, d7) and level 7 approximation coefficients (a7) of Daubechies 4 (db4), Daubechies 8 (db8), Symlet 5 (sym5), Symlet 7 (sym7), and Coiflet 5 (coif5) wavelets were calculated. In all the mentioned wavelets, DWT descriptors were extracted. Signals were reconstructed by inverse DWT. All data obtained by TD and DWT analyses were compared between the two groups. RESULTS: In both check sizes, a significant attenuation of N95 amplitude was seen in the patient group. The relative energy of a7 of db8 increased significantly in the POAG group in the 0.8° check size. In larger check stimuli, the relative energy of d7 of coif5 decreased significantly and the standard deviation of d7 of sym7 increased markedly in glaucomatous patients (P < 0.05). In small stimuli, N95 descriptor (7N) of db8 had the highest value and showed a significant increase as compared to the POAG group. In the 16° check size, there was no significant difference. A strong correlation was seen between reconstructed signals and originals (r = 0.99). CONCLUSION: The DWT can quantify PERG responses more accurately. In agreement with TD and wavelet coefficients domain results, 7N of db8 decomposition can be used as a good indicator for early detection of POAG.

A new surgical technique for excision of orbital cavernous hemangioma: a 15-year experience.

PURPOSE: To present a new surgical technique for excision of orbital cavernous hemangiomas (CHs). METHODS: This retrospective case series study included patients with orbital CH who were operated from 2001 to 2016 at our referral center. Epidemiologic data, symptoms, signs, and images were reviewed from patients' files with at least one year of follow-up. Surgical results and complications were documented. We used the "index finger dissection" technique without grasping the tumor for release of adhesions and its removal. RESULTS: We included 60 patients with orbital CH consisting of 36 (60%) female and 24 (40%) male patients with mean age of 40 ± 12.1 (range 9-66) years. The main complaint was proptosis with average size of 5.3 ± 2 millimeters. The surgical approach was lateral orbitotomy in 49 (81.7%) patients, medial transcutaneous in seven (11.7%) patients, inferior transconjunctival in three (5%) patients, and simultaneous lateral and medial orbitotomy in one (1.6%) patient. All tumors were removed intact; complications included ptosis in one subject, lower lid retraction in one case, and diplopia in two patients, all of which improved before 2 months. No optic nerve damage occurred. CONCLUSION: The "index finger dissection" technique without grasping the tumor for excision of orbital CH, via any external approach to the tumor, is a safe technique with minimal complications.

The Ocular Hypotensive Efficacy of Topical Fasudil, a Rho-Associated Protein Kinase Inhibitor, in Patients With End-Stage Glaucoma.

To investigate the effects of topical administration of a selective Rho-associated kinase (ROCK) inhibitor, fasudil 0.5% and 1.2% in glaucomatous patients. In this interventional case series study, 4 eyes of 4 patients with unilateral end-stage primary open-angle glaucoma and no light perception vision were assigned to receive topical fasudil 0.5% (in 3 eyes) or 1.2% (in 1 eye) ophthalmic solution twice daily for 8 weeks. At weeks 1, 2, 3, 4, and 8, intraocular pressure (IOP) and adverse events were evaluated. Baseline mean IOP was 53.5 ± 3.4 mm Hg and mean IOP reductions of the last visit were -8.25 ± 1.2 mm Hg at 2 hours and -8.75 ± 2.2 mm Hg at 4 hours. Mean IOP reductions were clinically and statistically significant with 0.5% and 1.2% fasudil and peak effects occurred 2-4 hours after application (P = 0.0002). The largest IOP reductions were produced by 1.2% fasudil (up to -12 mm Hg). Conjunctival hyperemia was found in 1 patient with 1.2% fasudil. Topical administration of fasudil in end-stage primary open-angle glaucoma patients, caused reduction in IOP and was well tolerated. ROCK inhibitors could be considered as a candidate for glaucoma therapy in future.

Biometric Changes After Trabeculectomy with Contact and Non-contact Biometry.

PURPOSE: To compare biometric changes measured with contact and noncontact methods after mitomycin-C-augmented trabeculectomy. METHODS: In this prospective study, 31 eyes from 31 glaucoma patients scheduled for primary trabeculectomy were enrolled. Biometric parameters including axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were measured using contact ultrasound biometry (UD-6000 Ultrasonic A/B scanner biometer; Tomey Corporation, Nagoya, Japan) and a noncontact optical biometry device (Lenstar; Haag-Streit AG, Koeniz, Switzerland). Measurements were taken the day before trabeculectomy and then compared with measurements obtained 3 and 6 months after surgery. RESULTS: The AL and ACD were significantly decreased at 3 and 6 months compared with baseline values taken with each biometry method. There was a significant increase in LT measured by the Lenstar device at the 3- and 6-month follow-up. At both the 3- and 6-month follow-up, the mean AL measurement reduction with the Lenstar device was significantly lower than that of the A-scan ultrasound measurements. The mean ACD changes between the two devices were not significantly different. CONCLUSIONS: There is a small but significant decrease in the AL and ACD after trabeculectomy as measured with both the contact and noncontact methods. The amount of AL reduction measured is significantly smaller using the noncontact method, making it the preferable method for intraocular lens power calculation for patients who need cataract surgery combined with or after trabeculectomy. The LT measured by the Lenstar device increased significantly after the operation, which can be an early sign of the progression of cataractous changes after trabeculectomy.

Peripapillary RNFL Thickness Changes after Panretinal Photocoagulation.

PURPOSE: To evaluate changes in peripapillary retinal nerve fiber layer (RNFL) thickness as determined by spectral domain optical coherence tomography (SD-OCT) after panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR). METHODS: Forty-two eyes of 42 diabetic patients who were scheduled for PRP were enrolled in this interventional case series. Peripapillary RNFL thickness was measured using SD-OCT (OCT 1000; Topcon Co., Tokyo, Japan) at baseline and 1, 3, and 6 months after PRP. RESULTS: Mean global RNFL thickness was increased significantly by 3 µm (p = 0.04) 1 month after PRP and was then decreased marginally significantly by 2.4 µm at 6 months (p = 0.054) as compared to baseline values. After 1 month, RNFL thickness was increased in all quadrants, but only changes in the temporal quadrant were significant (p = 0.009). At 6 months, progressive RNFL thinning occurred in all quadrants; however, only changes in the superior quadrant were significant (p = 0.041). Visual acuity was improved by an average of 0.02 logMAR after 6 months, but this change was not statistically significant. CONCLUSIONS: Shortly after PRP, RNFL thickness (as determined by SD-OCT) increases, but a decrease in RNFL thickness occurs at 6 months post-PRP. RNFL thickness changes based on OCT should be interpreted with caution in diabetic eyes undergoing PRP.

The p.Gly61Glu Mutation in CYP1B1 Affects the Extracellular Matrix in Glaucoma Patients.

PURPOSE: The aim of this work was to assess the possible effects of CYP1B1 mutations on the extracellular matrix (ECM) in glaucoma patients. CYP1B1 mutations are the cause of disease in a notable fraction of primary congenital glaucoma (PCG) patients and in a smaller fraction of primary open angle glaucoma (POAG) patients. METHODS: The study was performed on a glaucoma family with the common homozygous p.Gly61Glu CYP1B1 mutation. The father was affected with POAG and three siblings had PCG. Microscopy was performed on the skin of the father and one son, as well as controls. Immunohistochemical studies were done using anti-CYP1B1 and anti-fibrillin-1 antibodies. Fibrillin-1 served as a marker for the ECM, and electron microscopy was also performed. RESULTS: CYP1B1 expression patterns were the same in the patients and controls. However, microfibrils that are associated with fibrillin-1 were less abundant and more fragmented in both patients. Electron microscopy showed disturbed collagen fibers only in the PCG patient. CONCLUSIONS: The p.Gly61Glu mutation in CYP1B1 affects the ECM structure. This implies that the ECM of the trabecular meshwork may also be disrupted in a manner that affects aqueous humor flow resulting in increased intraocular pressure and contributing to the glaucoma phenotype.

Biometric parameters in different stages of primary angle closure using low-coherence interferometry.

PURPOSE: To compare ocular biometric parameters using low-coherence interferometry among siblings affected with different degrees of primary angle closure (PAC). METHODS: In this cross-sectional comparative study, a total of 170 eyes of 86 siblings from 47 families underwent low-coherence interferometry (LenStar 900; Haag-Streit, Koeniz, Switzerland) to determine central corneal thickness, anterior chamber depth (ACD), aqueous depth (AD), lens thickness (LT), vitreous depth, and axial length (AL). Regression coefficients were applied to show the trend of the measured variables in different stages of angle closure. To evaluate the discriminative power of the parameters, receiver operating characteristic curves were used. Best cutoff points were selected based on the Youden index. Sensitivity, specificity, positive and negative predicative values, positive and negative likelihood ratios, and diagnostic accuracy were determined for each variable. RESULTS: All biometric parameters changed significantly from normal eyes to PAC suspects, PAC, and PAC glaucoma; there was a significant stepwise decrease in central corneal thickness, ACD, AD, vitreous depth, and AL, and an increase in LT and LT/AL. Anterior chamber depth and AD had the best diagnostic power for detecting angle closure; best levels of sensitivity and specificity were obtained with cutoff values of 3.11 mm for ACD and 2.57 mm for AD. CONCLUSIONS: Biometric parameters measured by low-coherence interferometry demonstrated a significant and stepwise change among eyes affected with various degrees of angle closure. Although the current classification scheme for angle closure is based on anatomical features, it has excellent correlation with biometric parameters.

Intrasubject Difference in CCT among POAG versus Normal Individuals.

PURPOSE: To evaluate intrasubject asymmetry in central corneal thickness (CCT) among patients with primary open-angle glaucoma (POAG) as compared with that of normal subjects and to determine whether the eye with thinner cornea has more severe glaucomatous visual field damage. METHODS: In this case-control study, CCT of both eyes was measured using an ultrasonic pachymeter (UP-1000; Nidek Technologies, Gamagori, Japan) among POAG patients and normal subjects. The intrasubject difference in CCT was calculated and compared between the study groups; correlations between CCT and intraocular pressure (IOP), vertical cup-to-disc ratio (VCDR), and visual field defects were also evaluated. RESULTS: A total of 62 patients with bilateral POAG and 56 normal subjects were included. There was no significant difference between the study groups in terms of age, sex, and ocular parameters except for visual acuity, IOP, and VCDR. The POAG patients demonstrated significantly greater intrasubject asymmetry in CCT (8 ± 7 µm vs. 5 ± 3 µm; p = 0.041) and a higher prevalence of significant (>10 µm) intrasubject CCT difference (30.6 vs. 5.4%; p < 0.001) as compared with normal subjects. Although each higher level of glaucomatous damage was associated with 4-µm thinner CCT, the correlation was not statistically significant (95% confidence interval, -8 to 1 µm; p = 0.117; GEE analysis). No significant correlation was observed between CCT and IOP or VCDR (p = 0.302 and 0.137, respectively). CONCLUSIONS: Patients with POAG demonstrate a larger amount of intrasubject difference in CCT as compared with normal subjects.

Blepharoptosis Associated With Third Cranial Nerve Palsy.

PURPOSE: To evaluate the demographics and outcomes of management for blepharoptosis associated with third cranial nerve palsy at a tertiary eye center. METHODS: This retrospective cross-sectional and interventional study was performed on hospital records of patients with ptosis associated with third cranial nerve palsy who were referred to Labbafinejad Medical Center from January 1999 to January 2009. The authors evaluated age, sex, laterality, severity of involvement, etiology, clinical findings, and treatment modalities and outcomes in patients with blepharoptosis due to third cranial nerve palsy over a 10-year period. RESULTS: Of a total of 45 subjects, 25 cases (55.6%) were males and 20 subjects (44.4%) were females. Mean age of enrolled subjects was 21.1 ± 15.5 years. Etiologies included trauma in 21 (46.7%), congenital in 16 (35.6%), and other causes in 8 (17.7%) cases. Overall, 18 of 45 patients (40%) underwent ptosis surgery: of these, 15 (83.3%) subjects improved with one procedure, whereas 3 (16.7%) subjects required more than one operation. For initial ptosis surgery, 5 (27.7%) patients underwent levator resection and 13 (72.3%) cases underwent frontalis sling; all second and third procedures were frontalis sling. One-step, 2-step, and 3-step ptosis surgery was accomplished in 15 (83.3%), 1 (5.6%), and 2 (11.1%) patients, respectively. Eventually, an open visual axis was attained in all cases following 1-3 operations. CONCLUSIONS: Trauma was the most common cause of ptosis associated with third cranial nerve palsy in the current series. Surgical management of ptosis in patients with third nerve palsy may be challenging but most subjects achieve good results following appropriate and stepwise surgical plans.

Clinical and Radiologic Characteristics of Inferior Rectus Muscle Sheath Entrapment in Orbital Blowout Fracture.

Blowout fracture is a common condition in the oculoplastics clinic. One of the indications for its repair is entrapment of the inferior rectus muscle within the fracture site. Herein, the authors present 3 patients of inferior rectus muscle sheath entrapment without entrapment of the muscle itself. The outcome of treatment was excellent in all patients. The aim of this report is to present the special clinical and radiologic findings in such patients.

Tear condition following unilateral ptosis surgery.

PURPOSE: To evaluate changes in tear film condition following unilateral ptosis surgery. METHODS: This interventional case series includes patients with unilateral blepharoptosis scheduled for ptosis surgery with no prior history of eye disease and surgery over a 2-year period. Tear film evaluation before surgery were performed, which included Schirmer test with and without anesthesia, and tear break up time (TBUT). Ptosis surgery included levator resection and frontalis sling. The previously mentioned tests were repeated 1, 3, and 6 months after surgery. Subjective symptoms related to dry eye also evaluated before and after surgery. RESULTS: A total of 83 patients including 46 (55.4%) male subjects with mean age of 26.2 ± 16.2 years were enrolled in the study. The most common cause of ptosis was congenital in 77 (92.8%) patients. Surgical intervention included levator resection in 56 (67.5%) cases and frontalis sling procedure in 27 (32.5%) cases. The result of surgery was good in 47 (56.6%) patients while under- and overcorrection were observed in 32 (39.8%) and 3 (3.6%) patients, respectively. Schirmer's test with and without anesthesia and TBUT after surgery revealed a decrease in tear quantity and quality after surgery with time. Patients who had subjective complaints from dryness after surgery only had shorter TBUT among the objective signs. CONCLUSIONS: Ptosis surgery can decrease the quantity and quality of tears in operated eyes. Since some of these patients may need other types of operations in future, such as refractive or cataract surgery, evaluation of the tear condition before further surgery is prudent.

Effect of early treatment with aqueous suppressants on Ahmed glaucoma valve implantation outcomes.

OBJECTIVE: To evaluate the effect of early aqueous suppressant treatment on Ahmed glaucoma valve (AGV) surgery outcomes. DESIGN: Randomized clinical trial. PARTICIPANTS: Ninety-four eyes of 94 patients with refractory glaucoma. METHODS: After AGV implantation, 47 cases (group 1) received topical timolol-dorzolamide fixed-combination drops twice daily when intraocular pressure (IOP) exceeded 10 mmHg, whereas 47 controls (group 2) received conventional stepwise treatment when IOP exceeded target pressure. MAIN OUTCOME MEASURES: Main outcome measures included IOP and success rate (6 mmHg < IOP < 15 mmHg and IOP reduction of at least 30% from baseline). Other outcome measures included best-corrected visual acuity, complications, and hypertensive phase frequency. RESULTS: Groups 1 and 2 were both followed up for a mean of 45±11.6 and 47.2±7.4 weeks, respectively (P = 0.74). Mixed model analysis revealed a significantly greater IOP reduction in group 1 at all intervals (P<0.001). At 1 year, the cases exhibited a significantly higher success rate (63.2% vs. 33.3%; P = 0.008) and reduced hypertensive phase frequency (23.4% vs. 66.0%; P<0.001). CONCLUSIONS: Early aqueous suppressant treatment may improve AGV implantation outcomes in terms of IOP reduction, success rate, and hypertensive phase frequency.

The ocular hypotensive effect of saffron extract in primary open angle glaucoma: a pilot study.

BACKGROUND: The progressive nature of glaucoma and its growing incidence make its therapy an important target for research. The role of oxidative damage in the pathogenesis of glaucoma makes antioxidants such as saffron extract an attractive target for potential clinical use. Herein, we evaluate the effect of aqueous saffron extract on intraocular pressure (IOP) in eyes with primary open-angle glaucoma (POAG). METHODS: Thirty-four eyes of 34 clinically stable POAG patients receiving treatment with timolol and dorzolamide eye drops were enrolled in this prospective, comparative, randomized interventional pilot study. Eligible subjects were randomized to receive 30 mg/day aqueous saffron extract orally (17 subjects, 17 eyes) or placebo (17 subjects, 17 eyes) for one month as an adjunct to timolol and dorzolamide. Following treatment, both study groups entered a one-month wash-out period. The main outcome measure was IOP during treatment and after the wash-out period. RESULTS: Mean baseline IOP was 12.9 ± 3.7 versus 14.0 ± 2.5 mmHg in the saffron and control groups, respectively (p = 0.31). After three weeks of treatment, IOP was significantly decreased to 10.9 ± 3.3 mmHg in the saffron group as compared to 13.5 ± 2.3 mmHg in the control group (p = 0.013). At four weeks, IOP was still significantly lower in the saffron group (10.6 ± 3.0 versus 13.8 ± 2.2 mmHg, p = 0.001). At the end of the wash-out period, IOP was 12.9 ± 3.0 in the saffron group versus 14.2 ± 2.0 mmHg in the control group (p = 0.175). None of the patients experienced side effects during the study and wash-out period. CONCLUSIONS: Oral aqueous saffron extract seems to exert an ocular hypotensive effect in primary open-angle glaucoma. This effect became evident after three weeks of therapy.The current study was registered at the International Clinical Trials Registry Platform (ICTRP) as IRCT201201278832N1.

Free-floating pyogenic granuloma of the lacrimal sac.

The authors report a 13-month-old girl with chronic dacryocystitis, and history of three times probing and once inferior turbinate infracture. She underwent dacryocystorhinostomy due to failure of previous procedures. During surgery a free floating reddish mass was extracted from the lacrimal sac. Histopathologic examination revealed the mass to be a pyogenic granuloma.

Modification of a Selective NTRK2 Agonist and Confirmation of Activity in a Glaucoma-on-a-Chip Model.

Purpose: RNYK is a selective agonist of the neurotrophic tyrosine kinase receptor type 2 (NTRK2) which has been screened from a phage-displayed peptide library. Its sequence is SGVYKVAYDWQH, similar to a native NTRK2 ligand, that is, brain-derived neurotrophic factor (BDNF). The current study was performed to recognize and confirm critical residues for RNYK activity in a glaucoma-on-a-chip model. Methods: We designed a modified RNYK (mRNYK) peptide based on hotspots of the RNYK sequence identified by alanine scanning. The critical residues consisted of tyrosine, valine, aspartic acid, and tryptophan (YVDW); however, lysine and glutamine were also maintained in the final sequence (YKVDWQ) for forming amide bonds and peptide dimerization. The affinity of mRNYK binding was confirmed by testing against NTRK2 receptors on the surface of ATRA-treated SH-SY5Y cells. The neuroprotective effect of mRNYK was also evaluated in cell culture after elevated pressure insult in a glaucoma-on-a-chip model. Results: The primary amine on the lysine side-chain from one sequence (YKVDWQ) reacted with a γ-carboxamide group of glutamine from the other sequence, forming dimeric mRNYK. In silico, molecular dynamic simulations of the mRNYK-NTRK2 complex showed more stable and stronger interactions as compared to the RNYK-NTRK2 complex. In vitro, mRNYK demonstrated a neuroprotective effect on SH-SY5Y cells under normal and elevated pressure comparable to RNYK. The 50% effective concentration (logEC50) for mRNYK was 0.7009, which was better than RNYK with a logEC50 of 0.8318. Conclusion: The modified peptide studied herein showed improved stability over the original peptide (RNYK) and demonstrated potential for use as a BDNF agonist with neuroprotective properties for treatment of neurodegenerative disorders such as glaucoma.