Surgical outcomes of microincision vitrectomy surgery in eyes with retinal detachment secondary to retinopathy of prematurity in Indian population.

Purpose: To analyze and report outcomes of microincision vitrectomy surgery (MIVS) for Stage 4 and 5 retinopathy of prematurity (ROP). Methods: Medical records of 202 eyes of 129 premature children undergoing MIVS for Stage 4/Stage 5 ROP between January 2012 and April 2015 were evaluated. The primary outcome measure was the proportion of eyes with anatomical success (defined as attached retina at the posterior pole at last follow-up). Complications associated with MIVS were noted and analysis of risk factors associated with poor anatomical outcome was also done using logistic regression. Results: Mean age of presentation of babies with Stage 4 ROP (2.9 ± 1.75 months) was lower than those with stage 5 disease (5.62 ± 2.55 months) (P < 0.005). One hundred seventeen eyes (56% or 58%) had Stage 5, 38 (19%) had Stage 4a, and 47 (23%) Stage 4b. Ninety-four eyes (47%) had received prior treatment (laser and/or anti-vascular endothelial growth factors [VEGF]). Lens-sparing vitrectomy (LSV) was performed in 58 (29%) eyes while lensectomy with vitrectomy (LV) was performed in 144 (71%) eyes. At a mean follow-up of 32.5 weeks, 102 (50.5%) eyes achieved anatomical success, including 74% eyes in Stage 4a and 4b and 33% in Stage 5. Complications included intraoperative break formation (19%), postoperative vitreous hemorrhage (28%), raised intraocular pressure (12.7%), and cataract progression (2.4%). Factors significantly associated with favorable anatomical outcome were Stage 4 disease (vs. Stage 5) (odds ratio [OR] 5.8; confidence interval [CI] =2.6-13.8, P < 0.005), prior treatment (laser ± anti-VEGF) (OR 2.5; CI 1.4-4.7, P < 0.005) surgery with 25G MIVS (vs. 23G) (OR: 1.7; CI = 0.98-3.00, P = 0.05) and LSV (vs. LV) (OR 7; CI = 3.4-14.6, P < 0.005). Retinal break was significantly associated with poor anatomical outcome (OR 0.21; CI = 0.09-0.5, P < 0.005). Conclusion: MIVS along with wide angle viewing systems allow surgeons to effectively manage ROP surgeries while at the same time reducing complication rate in these eyes which have complex pathoanatomy and otherwise grim prognosis.

Solvation in mixed aqueous solvents from a thermodynamic cycle approach.

A novel approach is presented for interpreting and potentially predicting values of the isothermal, isobaric transfer free energy, entropy, and enthalpy (Deltamicrotr2, Deltastr2, and Deltahtr2) for a solute between water and water-cosolvent mixtures. The approach explicitly accounts for volumetric properties of the solvent and solute (the equation of state, EoS) and casts the overall transfer process as a thermodynamic cycle with two stages: (1) isothermal solvent exchange from pure water to the cosolvent composition of interest at fixed mass density; (2) isothermal expansion or compression at the final solvent composition to recover the pressure of the initial state. Using molecular simulations with methane as the solute, the analysis is illustrated over a wide range of cosolvent concentrations for sorbitol-, ethanol-, and methanol-water binary mixtures. The EoS contribution semiquantitatively or quantitatively captures Deltamicrotr2, Deltastr2, and Deltahtr2 in almost all cases tested, highlighting the importance of considering the effects of changes in solvent density on the overall transfer process. The results also indicate that apolar solvation at these length scales is dominated by the work of cavity formation across a range of cosolvent species and concentrations.

Molecular solvation in water-methanol and water-sorbitol mixtures: the roles of preferential hydration, hydrophobicity, and the equation of state.

Molecular dynamics simulations of aqueous mixtures of methanol and sorbitol were performed over a wide range of binary composition, density (pressure), and temperature to study the equation of state and solvation of small apolar solutes. Experimentally, methanol is a canonical solubilizing agent for apolar solutes and a protein denaturant in mixed-aqueous solvents; sorbitol represents a canonical "salting-out" or protein-stabilizing cosolvent. The results reported here show increasing sorbitol concentration under isothermal, isobaric conditions results in monotonic increases in apolar solute excess chemical potential (mu2ex) over the range of experimentally relevant temperatures. For methanol at elevated temperatures, increasing cosolvent composition results in monotonically decreasing mu2ex. However, at lower temperatures mu2ex exhibits a maximum versus cosolvent concentration, as seen experimentally for Ar in ethanol-water solutions. Both density anomalies and hydrophobic effects--characterized by temperatures of density maxima and apolar solute solubility minima, respectively--are suppressed upon addition of either sorbitol or methanol at all temperatures and compositions simulated here. Thus, the contrasting effects of sorbitol and methanol on solute chemical potential cannot be explained by qualitative differences in their ability to enhance or suppress hydrophobic effects. Rather, we find mu2ex values across a broad range of temperatures and cosolvent composition can be quantitatively explained in terms of isobaric changes in solvent density--i.e., the equation of state--along with the corresponding packing fraction of the solvent. Analysis in terms of truncated preferential interaction parameters highlights that care must be taken in interpreting cosolvent effects on solvation in terms of local preferential hydration.