B.Tech in Mechanical Engineering
M.Tech in CAD/CAM
Ph.D. in Biomechanics from IIT Hyderabad and Swinburne University in Technology
RESEARCH, TEACHING, or OTHER INTERESTS
Biomaterials, Mechanics of Materials, Multidisciplinary, Mechanical Engineering
16
Scopus Publications
Scopus Publications
Loss of retinal stem cell reserve and lipofuscin accumulation accelerates cone-rod degeneration and replicates Stargardt disease in abca4b null zebrafish Divya Pidishetty, Santhosh Kumar Damera, Murali Murugavel, Praveen Joseph Susaimanickam, Sai Naga Sri Harsha Chittajallu, Gopal Kushawah, Puja Sarkar, Shrikant R. Bharadwaj, Rakesh Mishra, Indumathi Mariappan Scientific Reports, 2025 Mutations in ABCA4 gene causes Stargardt macular degeneration, which manifests with toxic lipofuscin deposits in the outer retina, gradual atrophy of RPE cells, followed by photoreceptor cell loss. The cone-enriched retina, with macula-like ‘area-temporalis’ of zebrafish are better models than rodents for studying human macular dystrophies. Here, we generated abca4b knockout zebrafish model using CRISPR/Cas9 editing and evaluated the early and late-stage retinal changes. In adult abca4b −/− mutants, the RPE cells exhibited hyperpigmentation, altered retinomotor behaviour and lipofuscin accumulation, but they remained viable. However, the photoreceptors underwent progressive degeneration, with a sequential loss of blue and UV cones, followed by red and green cones and finally the rod cells. This triggered the chronic activation and early depletion of retinal stem cells at the ciliary marginal zone of mutants and resulted in accelerated outer-retinal degeneration and severe visual defects, despite them retaining the Müller glia-dependant retinal repair potential.
Collagen imaging reveals synergistic effects of sutures and host-donor misalignment on topographical irregularities in penetrating keratoplasty Himanshu Gururani, Sai Naga Sri Harsha Chittajallu, Minal Doulatramani, Viswanath Chinthapenta, Sayan Basu, Ramji M. Plos One, 2024 Purpose Mitigating unwanted refractive errors is crucial for surgeons to ensure quality vision after penetrating keratoplasty (PK). The primary objective of the present study is to highlight the importance of microstructural matching of the host and the donor cornea during PK on the distribution of the corneal tissue while suturing. Methods For this purpose, the present study undertakes an in-vitro PK model to analyse the effect of suturing and host-donor misalignment on corneal birefringence. Five groups of experiments were performed using five corneoscleral buttons. In each group, N = 16 data points (corresponding to 16 simple interrupted sutures) were assessed before and after PK with five degrees of misalignments, 0°, 30°, 45°, 60° and 90° to detect the variations in corneal birefringence post-PK. The technique of digital photoelasticity is utilized to capture the corneal birefringence experimentally. Results The local and global features of corneal birefringence provided interesting insights into the nuances of corneal birefringence in PK. Statistical analysis was performed to study the effects of suturing on the birefringence around the suture bites. It was observed that the interaction of the suture tension and structural misalignment between the host and the donor cornea influences the corneal birefringence in PK. Conclusions The zero-degree structural misalignment of the host and the donor tissue is preferable to minimize the topographical irregularities and related astigmatism post-PK. The findings of the present study envisage an additional step of structurally aligning the donor tissue with the host before suturing to minimize topographical irregularities in PK.
Investigation of mechanical strength and structure of corneal graft-host junction Sai Naga Sri Harsha Chittajallu, Himanshu Gururani, Saumya Jakati, Sayan Basu, Pravin Krishna Vaddavalli, Kwong Ming Tse, Viswanath Chinthapenta Heliyon, 2024 Dehiscence is a common complication of corneal transplant surgery involving separating the graft from the host eye. The present article aims to investigate fundamental insights into the mechanical and structural aspects of the graft-host junction (GHJ) of a graft that survived in a patient for 13 years after penetrating keratoplasty (PK). Additionally, it adopts the sutur retention strength (SRS) test procedure defined in ISO:7198-2016 and aims to provide a comprehensive test protocol to study the biomechanics of the GHJ in extracted PK buttons. A 9 mm corneal button with GHJ was extracted from a 46-year-old patient who underwent PK 13 years back. The strength of the GHJ was quantified using the SRS test. Corresponding control results were obtained from the SRS tests of a corneoscleral button with no history of any refractive procedure. Birefringence, histological, and scanning electron microscopy (SEM) imaging were used to visualize the microstructural details of the GHJ. The strength of the GHJ was observed to be ten times lower than the native cornea. Histopathological features, such as fragmented Bowman's layer, and fibrosis with a clear demarcation line between host and graft tissue, were observed at the GHJ, suggesting a weak bond across the GHJ. The low strength of the GHJ in PK indicates the high susceptibility of the GHJ towards wound dehiscence.
Intraoperative collagen imaging of sutured cornea: A way towards managing post-penetrating keratoplasty astigmatism Himanshu Gururani, Sai Naga Sri Harsha Chittajallu, Minal Doulatramani, Ramji Manoharan, Sayan Basu, Viswanath Chinthapenta Medical Engineering and Physics, 2024 The birefringent nature of the human cornea plays an important role in comprehending its structural behavior in both diseased and surgical conditions. During corneal transplantation, irregular astigmatism is a common post-surgical complication that depends on the characteristics of suturing. Four human cadaver corneas are subjected to an in-vitro model of a typical full-thickness penetrating keratoplasty (PK) procedure using 16 simple interrupted 10-0 vicyrl sutures. The birefringence of these four corneas is analyzed using digital photoelasticity and compared with the control cornea (without PK). It is found that the sutures and their mutual interaction influence the morphology of the peripheral birefringence of the cornea. The findings of the present investigation are pertinent to intraoperative suture management during PK. Results suggest conserving the typical diamond-shaped morphology of peripheral birefringence would ensure uniform distribution of sutures. Therefore, birefringence imaging could be useful in suture management to ensure proper apposition of the graft-host junction, thus minimizing the risk of irregular astigmatism.
Investigation of microstructural failure in the human cornea through fracture tests Sai Naga Sri Harsha Chittajallu, Himanshu Gururani, Kwong Ming Tse, Subha Narayan Rath, Sayan Basu, Viswanath Chinthapenta Scientific Reports, 2023 Fracture toughness of the human cornea is one of the critical parameters in suture-involved corneal surgeries and the development of bioengineered mimetics of the human cornea. The present article systematically studied the fracture characteristics of the human cornea to evaluate its resistance to tear in the opening (Mode-I) and trouser tear mode (Mode-III). Tear experiments reveal the dependency of the fracture behavior on the notch size and its location created in the corneal specimens. The findings indicate lamellar tear and collagen fiber pull-out as a failure mechanism in trouser tear and opening mode tests, respectively. Experimental results have shown a localized variation of tear behavior in trouser tear mode and indicated an increasing resistance to tear from the corneal center to the periphery. This article demonstrated the complications of evaluating fracture toughness in opening mode and showed that the limbus was weaker than the cornea and sclera against tearing. The overall outcomes of the present study help in designing experiments to understand the toughness of the diseased tissues, understanding the effect of the suturing location and donor placement, and creating numerical models to study parameters affecting corneal replacement surgery.
Development and validation of a ‘MyLyt’ wearable light tracking device Rohit Dhakal, Jagadesh Rao Rudrapankte, Harsha S. N. S. Chittajallu, John G. Lawrenson, Byki Huntjens, Rakhee Shah, Pavan K. Verkicharla Ophthalmic and Physiological Optics, 2023 PurposeWe developed a clip‐on light tracker (MyLyt) for estimating light exposure in real time. This study aimed at validating and investigating the feasibility of using MyLyt in children and adults.MethodThe study was conducted in two phases. Phase 1 involved validation against a factory‐calibrated digital lux meter in three separate conditions: controlled environmental set‐up, outdoors and indoors where intra‐test (two measurements by the same tracker), inter‐test (measurements among trackers) and inter‐device (MyLyt tracker and lux meter) validations were conducted. Phase 2 involved a feasibility study where MyLyt was used in a real‐world setting by 21 adults and 8 children. Participants were asked to log their real‐time movements in an ‘activity diary’, which were correlated with the lux levels measured by the tracker.ResultsA strong positive correlation and non‐significant difference in the recorded mean illuminance levels were observed during intra‐test (inter‐class correlation: 1.00, p = 0.99), inter‐test (0.91–1.00, p > 0.15) and inter‐device (0.91–1.00, p > 0.56) validation in all three testing conditions (p > 0.49), except the indoor location. While the lux level measured by MyLyt was significantly higher than that of the lux meter (p < 0.01) in the indoor locations, differences were minimal and clinically insignificant. A Bland–Altman plot showed a minimal mean difference (95% limits of agreement) between the MyLyt tracker and lux meter in all three conditions (controlled environmental set‐up: 641 [−949, 2230], outdoor: 74 [−2772, 2920] and indoor: −35 [−151, 80] lux). Phase 2 validation showed an expected illuminance level against the corresponding location with high sensitivity (97.8%) and specificity (99%) to accurately differentiate between outdoor and indoor locations.ConclusionThe MyLyt tracker showed good repeatability, strong correlation and comparable values with the lux meter in the three tested conditions, making it suitable for tracking light exposure patterns for both research and clinical purposes.
A Review on Damage and Rupture Modelling for Soft Tissues Sai Naga Sri Harsha Chittajallu, Ashutosh Richhariya, Kwong Ming Tse, Viswanath Chinthapenta Bioengineering, 2022 Computational modelling of damage and rupture of non-connective and connective soft tissues due to pathological and supra-physiological mechanisms is vital in the fundamental understanding of failures. Recent advancements in soft tissue damage models play an essential role in developing artificial tissues, medical devices/implants, and surgical intervention practices. The current article reviews the recently developed damage models and rupture models that considered the microstructure of the tissues. Earlier review works presented damage and rupture separately, wherein this work reviews both damage and rupture in soft tissues. Wherein the present article provides a detailed review of various models on the damage evolution and tear in soft tissues focusing on key conceptual ideas, advantages, limitations, and challenges. Some key challenges of damage and rupture models are outlined in the article, which helps extend the present damage and rupture models to various soft tissues.
Is ahmed glaucoma valve consistent in performance? Nikhil S. Choudhari, Swathi Vallabh Badakere, Ashutosh Richhariya, Sai Naga Sri Harsha Chittajallu, Sirisha Senthil, Chandra Sekhar Garudadri Translational Vision Science and Technology, 2018
Effect of plane stress and plane strain conditions over fracture parameters of ductile plate in SSY (LEFM) and EPFM regimes: A review Advances in Civil Engineering and Building Materials Selected Peer Reviewed Papers from 2012 2nd International Conference on Civil Engineering and Building Materials Cebm 2012, 2012
