Purpose. To determine the significance of any association between intersessional changes in ocular residual astigmatism (RA) and astigmatism at corneal front (FSA) and back (BSA) surfaces following uneventful routine phacoemulsification. Methods. Astigmatism was evaluated by autorefractometry and subjective refraction and at both the corneal surfaces with Orbscan II™ (Bausch & Lomb) over central 3 mm and 5 mm optical zones at 1, 2, and 3 months after routine phacoemulsification in 103 patients implanted with monofocal nontoric intraocular lenses (IOLs, one eye/patient). Data were subjected to vector analysis to determine the actual change (Δ) in astigmatism (power and axis) for the refractive and Orbscan II findings. Results. The number of cases that attended where ΔRA was ≥0.50 DC between 1 and 2 months was 52 by autorefractometry and 36 by subjective refraction and between 2 and 3 months was 24 by autorefractometry and 19 by subjective refraction. Vector analysis revealed significant correlations between ΔFSA and ΔRA for data obtained by autorefractometry but not by subjective refraction. At all times, ΔBSA was greater than ΔFSA (p<0.01). Key findings for ΔBSA values over the central 3 mm zone were between (A) the sine of the axis of ΔRA (y) and sine of the axis of ΔBSA (x) for the data obtained by autorefractometry (between 1 and 2 months, y = 0.749 − 0.303x, r = 0.299, n = 52, p=0.031) and subjective refraction (between 2 and 3 months, y = 0.6614 − 0.4755x, r = 0.474, n = 19, p=0.040) and (B) ΔRA (y) and ΔBSA (x) powers between 2 and 3 months postoperatively for the data obtained by autorefractometry (ΔRA = 0.118 ΔBSA + 0.681 r = 0.467, n = 24, p=0.021) and subjective refraction (ΔRA = 0.072 ΔBSA + 0.545 r = 0.510, n = 19, p=0.026). Conclusion. Changes in the ocular residual refractive astigmatic error after implanting a monofocal nontoric IOL are associated with changes in astigmatism at the back surface of the cornea within the central optical zone.

Purpose: To determine the significance of any association between either change in angle kappa (K°) or the rectilinear displacement ( L , mm) of the first Purkinje image relative to the pupil center and unexpected changes in astigmatism after phacoemulsification. Methods: Orbscan II (Bausch and Lomb) measurements were taken at 1, 2, and 3 months after unremarkable phacoemulsification in patients implanted with spherical (group 1, SA60AT, Alcon) or aspheric (group 2, SN60WF, Alcon) nontoric IOLs. The outputs were used to calculate L . Astigmatism, measured by autorefractometry and subjective refraction, was subjected to vector analysis (polar and cartesian formats) to determine the actual change induced over the periods 1–2 and 2–3 months postop. Results: Chief findings were that the mean ( n , ±SD, 95%CI) values for L over each period were as follows: Group 1, 0.407 (38, ±0.340, 0.299–0.521), 0.315 (23, ±0.184, 0.335–0.485); Group 2, 0.442 (45, ±0.423, 0.308–0.577), 0.372 (26, ±0.244, 0.335–0.485). Differences between groups were not significant. There was a significant linear relationship between (A) the change in K (ΔK = value at 1 month-value at 2 months) and K at 1 month ( x ), where ΔK =0.668-3.794X ( r = 0.812, n = 38, P = <0.001) in group 1 and ΔK = 0.263 x -1.462 ( r = 0.494, n = 45, P = 0.002) in group 2, (B) L and the J 45 vector describing the actual change in astigmatism between 1 and 2 months in group 2, where J 45 (by autorefractometry) =0.287 L -0.160 ( r = 0.487, n = 38, P = 0.001) and J 45 (by subjective refraction) =0.281 L -0.102 ( r = 0.490, n = 38, P = 0.002), and (C) J 45 and ΔK between 2 and 3 months in group 2, where J 45 (by subjective refraction) =0.086ΔK-0.063 ( r = 0.378, n = 26, P = 0.020). Conclusion: Changes in the location of the first Purkinje image relative to the pupil center after phacoemulsification contributes to changes in refractive astigmatism. However, the relationship between the induced change in astigmatism resulting from a change in L is not straightforward.

Purpose: The aim of this study was to determine the effect of routine uncomplicated phacoemulsification on the orthogonal distribution of mass within the central optical zone of the cornea. Methods: Astigmatism at both corneal surfaces was evaluated using Orbscan II (Bausch &and Lomb) before and up to 3 months after routine phacoemulsification (one eye/patient). The data were subjected to vector analysis to estimate the pre-and postoperative total astigmatism of the cornea (TCA). Results: Reporting the chief findings in minus cylinder (diopters, DC) over the central 3 mm (A) and 5 mm (B) optical zones. Mean TCA powers (±sd) at pre- and 3-months postop were A) –4.45DC (±2.00) and –5.69DC (±2.69), B) –2.91DC (±2.22) and –2.71DC (±1.60). Change in mean power was significant over 3 mm ( P < 0.01, n = 49) but not over 5 mm. Inter-zonal differences were significant ( P < 0.01). There was a significant linear relationship between the change in TCA power ( y = preoperative-postoperative) and TCA at preoperative stage (x) where, A) y = 0.45x + 3.12 ( r = 0.336, n = 49, P = 0.018), B) y = x + 2.65 ( r = 0.753, n = 49, P = <0.01). Over the central 3 mm zone only, change (preoperative-postoperative) in axis (°) of TCA (y 1 ) was significantly associated with TCA axis at preoperative stage (x 1 ) where y 1 = 1.391x 1 -0.008x 1 2 -0.701 ( r = 0.635, n = 49, P < 0.01). Conclusion: Changes in TCA power and axis at 3 months postop, determined using Orbscan II, are indicative of orthogonal alterations in the distribution of corneal tissue. Over the central 3 mm zone, the association between y 1 and x 1 shows that a change in TCA axis is more profound when preoperative axis is near 90° i.e., against-the-rule.

Purpose: The aim of this study was to test a method for estimating corneal rigidity before and after cross-linking (CXL) using a Schiøtz tonometer. Methods: The study was performed in the Kyiv City Clinical Ophthalmological Hospital “Eye Microsurgical Center”, Ukraine. This was a prospective, consecutive, randomized, masked, case-by-case, clinical study. Corneal rigidity, indicated by the gradient (G) between lg applied weight and corresponding lg scale reading during Schiøtz tonometry, were obtained by increasing (A-mode) then reducing (D-mode) weights by two operators [A] in keratoconus, post-CXL and control subjects for estimation of (i) interoperator and (ii) intersessional errors, (iii) intergroup differences; [B] before and after CXL. Central corneal thickness CCT was measured by scanning slit pachymetry. ANOVA, t tests, linear regression were the statistical tools used. Results: Average interoperator difference (ΔG) was –0.120 (SD = ±0.294, 95%CI = –0.175 to –0.066). A significant correlation between ΔG and the mean of each pair of G values was found ( r = –0.196, n = 112, P = 0.038). Intersessional differences in mean G values were insignificant ( P > 0.05). There was a significant correlation between G at first session (X 1 ) and difference between sessions (ΔG) [Operator 1, ΔG = 0.598x 1 –0.461, r = 0.601, n = 27, P = 0.009]. Significant intergroup differences in G were found (Operator 1, one-way ANOVA, F = 4.489, P = 0.014). The difference (Δ) between the pre-(X 2 ) and post-CXL treatment G values was significantly associated with the pre-CXL treatment value (Operator 1, Δ = 1.970x 2 -1.622, r = 0.642, n = 18, P = <.001). G values were correlated with CCT in keratoconus and post-CXL. Conclusion: Corneal rigidity (G) estimated using the Schiøtz tonometer can be useful for detecting changes after CXL. However, G values are linked to CCT, can vary from time-to-time and the procedure is operator dependent.

Вплив буферних систем і консервантів у складі очних крапель на безпечне й тривале лікування пацієнтів із хворобою сухого ока Резюме. У статті висвітлено особливості різних складових офтальмологічних препаратів, залежність ефективності й переносимості терапії хвороби сухого ока від властивостей і характеристик очних крапель. Основу медикаментозної терапії протягом останніх років становлять препарати штучної сльози, або сльозозамінники. До їх складу входять різні буферні системи й консерванти. Детально висвітлені питання впливу консервантів, буферних систем на очну поверхню й можливість застосування альтернативних засобів. Наведено дані доклінічних і клінічних досліджень, які підтверджують переваги виключення консервантів зі складу очних крапель і наявність ризику виникнення ускладнень при тривалому застосуванні препаратів із консервантами.