Nucleus drop following phacoemulsification surgery: Incidence, risk factors and clinical outcomes.

PURPOSE: To determine the incidence, risk factors and clinical outcomes in patients with nucleus drop (ND) following phacoemulsification surgery at a tertiary care ophthalmic institute. METHODS: Medical records of patients with ND during phacoemulsification between January'2019 and December'2022 were reviewed retrospectively. Incidence of ND was calculated overall, and according to surgical expertise levels and surgical steps. Associated pre- and intra-operative risk factors were assessed. Clinical outcome parameters [best-corrected visual acuity (BCVA) and intraocular pressure (IOP)] were compared with respect to timing of PPV (immediate vs early vs delayed), location (sulcus vs scleral fixated-IOL) and timing of IOL placement (primary vs secondary). RESULTS: Among 93,760 phacoemulsifications, ND was noted in 130 patients (0.1%). Significant direct and associated pre-operative risk factors were advanced cataract, glaucoma, posterior polar cataract, and diabetes mellitus. Junior medical consultants had 40 ND (mostly in non-complex cases), whereas senior medical consultants had 90 ND (mostly in complex cases). ND most frequently occurred during emulsification of nuclear fragments. Sulcus placement of IOL during primary surgery yielded significantly better visual outcome compared to secondary procedures, although timing of PPV had insignificant effect. 77.1% had BCVA of 6/12 or better at final follow-up. Timing of IOL implantation, PPV, and type of IOL did not have any significant effect on IOP. CONCLUSIONS: Though the incidence of ND is low, it is a dreaded complication. Accurate pre-operative evaluation, risk stratification, distribution of cases among surgeons based on their surgical expertise, and immediate or early management of ND yields better anatomical and functional outcomes.

Evaluation of the impact of short term manual small incision cataract surgery (MSICS) training program on trainees with varying prior surgical experience using international council of ophthalmology-ophthalmology surgical competency assessment rubrics (ICO-OSCAR).

PURPOSE: To assess the learning curve of MSICS in three different groups of trainees with varying prior MSICS experience. To evaluate the effectiveness of ICO OSCAR for objective assessment of surgical skill transfer. METHODS: Ninety-five MSICS trainees were divided into three groups as 1st year resident, fellow and external trainee. Each group were evaluated for their surgical skill acquisition during one month MSICS training program using ICO-OSCAR. Each trainee performed an average of 19 surgeries. The progress in the learning curve of the three groups of trainees was analyzed by evaluating the mean scores in sets of five consecutive cases. Complications during the training period were also noted. RESULTS: The study evaluated a total of 1842 cases. The fellows and external trainees, with prior MSICS experience, had an initial mean score of 57.57 ± 16.16 and 56.86 ± 17.82 respectively, whereas the 1st year resident group had a relatively low initial mean score of 45.91(p = 0.009). The difference in mean scores between the 1st year resident group and other groups significantly reduced towards the end of training. The most common complications made by 1st year residents were in sclero-corneal tunnel construction. The external trainee group had statistically significant higher rates of zonular dialysis in the study. CONCLUSIONS: ICO-OSCAR is an effective tool for assessing MSICS training program. Structured short term MSICS surgical training program is effective in surgical skill transfer, especially in novice surgeons.

Outcomes of cataract surgery in patients with Human Immunodeficiency Virus infection in a developing country.

PURPOSE: To report the outcomes of cataract surgery in patients with Human Immunodeficiency Virus (HIV) infection. Setting Tertiary care ophthalmic hospital DESIGN: Retrospective study METHODS: This study included all eyes of patients with known HIV infection undergoing cataract surgery with a minimum follow-up of 6 months between January 2017 and December 2020. Patients who underwent combined surgeries and pediatric patients were excluded from analysis. Data were retrieved from electronic medical records and we documented demographics, history, detailed anterior and posterior segment examination, pre-operative grade and type of cataract, type of surgery done, its complication and post-operative course. All these parameters were recorded at the baseline visit and at 1 month and 6 months postoperatively. RESULTS: One hundred and twenty nine eyes of 107 HIV infected patients that underwent cataract surgery were evaluated. Mature cataract was seen in 31% of the eyes. Features of HIV related uveitis/retinitis were seen in 21 (16.2%) eyes. Phacoemulsification was performed in 44 (34.1%) eyes while manual small incision cataract surgery (MSICS) was done in 85 (65.9%) eyes. Intra-operative complications were encountered in 4 (3.1%) eyes. At the final follow-up, there was a significant improvement in median corrected distance visual acuity (CDVA) from LogMAR 1.08 (5/60) at baseline to LogMAR 0 (6/6) at 6 months follow-up. CONCLUSION: Patients with HIV infection usually present early and with advanced cataracts. Visual outcomes after cataract surgery are generally good but affected by presence of prior HIV related uveitis or retinitis.

Outcomes of manual small incision cataract surgery (MSICS) in eyes with corneal opacity.

PURPOSE: To report the outcomes of manual small incision cataract surgery (MSICS) in eyes with corneal opacity. SETTING: Tertiary care ophthalmic hospital. DESIGN: Retrospective study. METHODS: This retrospective study included 286 eyes of 286 patients having cataract with a pre-existing corneal opacity who underwent manual small incision cataract surgery (MSICS) at a tertiary eye institute between January 2020 and January 2022. Data were retrieved from electronic medical records, and we documented demographics, history, detailed anterior and posterior segment examination, cataract grading, pre- and post-operative vision, intra-operative complications and its management, and post-operative course. All these parameters were recorded at the baseline visit, day 1 and at 1 month post-operatively. RESULTS: Two hundred eighty-six eyes having cataract with a pre-existing corneal opacity which underwent MSICS were evaluated. Corneal opacity was graded as nebular, nebulo-macular, macular and leucomatous types; nebular opacity being the most common. Trauma was the most common cause of opacity followed by infective keratitis. Intra-operative complication rate was 4.89%; which included-7 posterior capsular rent with vitreous disturbance, 2 zonular dialysis, 2 iridodialysis, 2 eyes with aphakia and 1 with Descemet membrane detachment. On follow-up, 6 patients had decentered intraocular lens and 10 had residual cortex. Median logMAR vision improved significantly (p < 0.001) from 1.08 (5/60) pre-operatively to 0.3 (6/12) post-operatively. CONCLUSION: MSCIS is efficient in providing favorable visual outcomes in patients where corneal opacity makes it difficult for the surgeon to perform a phacoemulsification surgery.

Cataract surgery in colobomatous eyes with advanced cataract.

BACKGROUND: Cataract surgeries are challenging in colobomatous eyes as they are associated with features such as microphthalmia, microcornea, zonular deficit, etc. These factors predispose to capsulorhexis extension, posterior capsular rent, zonular dialysis and result in unfavourable visual outcomes. The most critical step of cataract surgery in such cases is the capsulorhexis as the chances of extension are high in the colobomatous area. In presence of pre-existing zonular dehiscence, nucleus management becomes more challenging in advanced cataracts. PURPOSE: To illustrate efficient management of advanced cataract in colobomatous eyes. SYNOPSIS: A 39-year old lady presented with complaints of gradually progressive diminution of vision in both eyes. Examination revealed bilateral nuclear sclerosis grade III-IV with irido-lenticular retinochoroidal coloboma (ILRCC). The patient was scheduled for bilateral cataract surgery after a thorough evaluation. Initially, the left eye was planned for phacoemulsification, in the course of which capsulorhexis extension occurred, leading to nucleus tilt and vitreous disturbance during emulsification. Automated anterior vitrectomy was done and the surgical approach was shifted to manual small incision cataract surgery (MSICS) with 3-piece intraocular lens placement in sulcus. The right eye was hence planned for MSICS and a rhexis extension was noted in this eye as well. Comparing the outcome of both the surgeries it was noted that both had capsulorhexis extension, but the management of nucleus and intraocular lens implantation was efficient in case of MSICS than phacoemulsification. Posterior chamber intraocular lens were placed in both eyes and the patient attained good visual outcome. HIGHLIGHTS: MSICS is a better approach to cases of ILRCC with advanced cataract. The capsulo should be tailored according to the site of coloboma such that it should be smaller in the area involving the coloboma and larger away from it. VIDEO LINK: https://youtu.be/d9FC0eavhRs.

Comparison of two phacoemulsification system handpieces: prospective randomized comparative study.

PURPOSE: To compare the safety and efficacy of Active Sentry handpiece with Ozil handpiece for Centurion phacoemulsification system. SETTING: Tertiary eye center, South India. DESIGN: Prospective observational study. METHODS: 204 eyes of 204 patients with uncomplicated cataract who underwent phacoemulsification cataract surgery with Centurion Vision System were randomized into 2 groups: Ozil handpiece (n = 101) and Active Sentry handpiece (n = 103). Intraoperative factors such as patient pain perception, surgeon comfort level, amount of phacoemulsification energy and aspiration fluid used, and frequency of activation of active surge mitigation (ASM) were analyzed, and postoperatively, corrected distance visual acuity (CDVA) and corneal edema on day 1 were compared. RESULTS: A total of 204 eyes of 204 patients were included among which 101 underwent surgery with ozil hand piece and 103 with Active Sentry handpiece. Patient pain perception was comparable between the groups with no statistically significant differences in patients who had pain-free surgery (66% vs 61.3%) and those who experienced moderate pain (24.3% vs 28.7%). Surgeons were more comfortable using Ozil handpiece during entry into anterior chamber and emulsification of hard nuclei (48.5% vs 28.6%). The mean cumulative dissipated energy for soft and hard cataracts was 5.6 and 4.8 and 9.3 and 9.4 for Ozil and Active Sentry groups, respectively. ASM was activated for 53 eyes (51.5%), of which 42 eyes (79.2%) had soft cataract and 11 eyes (20.7%) hard cataract. Postoperative CDVA and incidence of corneal edema were comparable between the groups. CONCLUSIONS: For Centurion Vision System, Active Sentry handpiece was as safe and efficacious as the Ozil handpiece with added benefit of operating at lower intraocular pressure levels.

Corrigendum: Isolation and Taxonomic Characterization of Novel Haloarchaeal Isolates From Indian Solar Saltern: A Brief Review on Distribution of Bacteriorhodopsins and V-Type ATPases in Haloarchaea.

[This corrects the article DOI: 10.3389/fmicb.2020.554927.].

Isolation and Taxonomic Characterization of Novel Haloarchaeal Isolates From Indian Solar Saltern: A Brief Review on Distribution of Bacteriorhodopsins and V-Type ATPases in Haloarchaea.

Haloarchaea inhabit high salinity environments worldwide. They are a potentially rich source of crucial biomolecules like carotenoids and industrially useful proteins. However, diversity in haloarchaea present in Indian high salinity environments is poorly studied. In the present study, we isolated 12 haloarchaeal strains from hypersaline Kottakuppam, Tamil Nadu solar saltern in India. 16S rRNA based taxonomic characterization of these isolates suggested that nine of them are novel strains that belong to genera Haloarcula, Halomicrobium, and Haloferax. Transmission electron microscopy suggests the polymorphic nature of these haloarchaeal isolates. Most of the haloarchaeal species are known to be high producers of carotenoids. We were able to isolate carotenoids from all these 12 isolates. The UV-Vis spectroscopy-based analysis suggests that bacterioruberin and lycopene are the major carotenoids produced by these isolates. Based on the visual inspection of the purified carotenoids, the isolates were classified into two broad categories i.e., yellow and orange, attributed to the differences in the ratio of bacterioruberin and lycopene as confirmed by the UV-Vis spectral analysis. Using a PCR-based screening assay, we were able to detect the presence of the bacteriorhodopsin gene (bop) in 11 isolates. We performed whole-genome sequencing for three bop positive and one bop negative haloarchaeal isolates. Whole-genome sequencing, followed by pan-genome analysis identified multiple unique genes involved in various biological functions. We also successfully cloned, expressed, and purified functional recombinant bacteriorhodopsin (BR) from one of the isolates using Escherichia coli as an expression host. BR has light-driven proton pumping activity resulting in the proton gradient across the membrane, which is utilized by V-Type ATPases to produce ATP. We analyzed the distribution of bop and other accessory genes involved in functional BR expression and ATP synthesis in all the representative haloarchaeal species. Our bioinformatics-based analysis of all the sequenced members of genus Haloarcula suggests that bop, if present, is usually inserted between the genes coding for B and D subunits of the V-type ATPases operon. This study provides new insights into the genomic variations in haloarchaea and reports expression of new BR variant having good expression in functional form in E. coli.

Biochemical and Taxonomic Characterization of Novel Haloarchaeal Strains and Purification of the Recombinant Halotolerant α-Amylase Discovered in the Isolate.

Haloarchaea are salt-loving archaea and potential source of industrially relevant halotolerant enzymes. In the present study, three reddish-pink, extremely halophilic archaeal strains, namely wsp1 (wsp-water sample Pondicherry), wsp3, and wsp4, were isolated from the Indian Solar saltern. The phylogenetic analysis based on 16S rRNA gene sequences suggests that both wsp3 and wsp4 strains belong to Halogeometricum borinquense while wsp1 is closely related to Haloferax volcanii species. The comparative genomics revealed an open pangenome for both genera investigated here. Whole-genome sequence analysis revealed that these isolates have multiple copies of industrially/biotechnologically important unique genes and enzymes. Among these unique enzymes, for recombinant expression and purification, we selected four putative α-amylases identified in these three isolates. We successfully purified functional halotolerant recombinant Amy2, from wsp1 using pelB signal sequence-based secretion strategy using Escherichia coli as an expression host. This method may prove useful to produce functional haloarchaeal secretory recombinant proteins suitable for commercial or research applications. Biochemical analysis of Amy2 suggests the halotolerant nature of the enzyme having maximum enzymatic activity observed at 1 M NaCl. We also report the isolation and characterization of carotenoids purified from these isolates. This study highlights the presence of several industrially important enzymes in the haloarchaeal strains which may potentially have improved features like stability and salt tolerance suitable for industrial applications.

Discovery of bacteriorhodopsins in Haloarchaeal species isolated from Indian solar salterns: deciphering the role of the N-terminal residues in protein folding and functional expression.

Interesting optical and photochemical properties make microbial rhodopsin a promising biological material suitable for various applications, but the cost-prohibitive nature of production has limited its commercialization. The aim of this study was to explore the natural biodiversity of Indian solar salterns to isolate natural bacteriorhodopsin (BR) variants that can be functionally expressed in Escherichia coli. In this study, we report the isolation, functional expression and purification of BRs from three pigmented haloarchaea, wsp3 (water sample Pondicherry), wsp5 and K1T isolated from two Indian solar salterns. The results of the 16S rRNA data analysis suggest that wsp3, wsp5 and K1T are novel strains belonging to the genera Halogeometricum, Haloferax and Haloarcula respectively. Overall, the results of our study suggest that 17 N-terminal residues, that were not included in the gene annotation of the close sequence homologues, are essential for functional expression of BRs. The primary sequence, secondary structural content, thermal stability and absorbance spectral properties of these recombinant BRs are similar to those of the previously reported Haloarcula marismortui HmBRI. This study demonstrates the cost-effective, functional expression of BRs isolated from haloarchaeal species using E. coli as an expression host and paves the way for feasibility studies for future applications.

Bacteriorhodopsin-ZnO hybrid as a potential sensing element for low-temperature detection of ethanol vapour.

Zinc oxide (ZnO) and bacteriorhodopsin (bR) hybrid nanostructures were fabricated by immobilizing bR on ZnO thin films and ZnO nanorods. The morphological and spectroscopic analysis of the hybrid structures confirmed the ZnO thin film/nanorod growth and functional properties of bR. The photoactivity results of the bR protein further corroborated the sustainability of its charge transport property and biological activity. When exposed to ethanol vapour (reducing gas) at low temperature (70 °C), the fabricated sensing elements showed a significant increase in resistivity, as opposed to the conventional n-type behaviour of bare ZnO nanostructures. This work opens up avenues towards the fabrication of low temperature, photoactivated, nanomaterial-biomolecule hybrid gas sensors.