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We report a method to insert a 3-piece AcrySof MA30BA acrylic foldable intraocular lens (IOL) (Alcon) in a single action using a Monarch II (Alcon) injector. The technique was used in 134 eyes. The incision widths ranged from 3.00 to 3.75 mm. The IOLs were successfully inserted in the capsular bag. Complications included cracks in the IOL optic in 3 eyes (3%), haptic damage in 3 eyes (3%), and inadequate self-sealing of the incision in 18 eyes (13%).

We investigated mechanisms by which intracellular pH was regulated under intracellular acidic condition in resting guinea-pig ventricular papillary muscles in vitro. Intracellular sodium ion activity (aiNa), intracellular and surface pH (pHi and pHs) were measured with Na(+)- and H(+)-selective microelectrodes and resting tension was measured. By exposure to 0 mM K solution aiNa and resting tension increased progressively while pHi decreased but reached the steady level of pH 6.95. pHs which was lower than external bulk pH (pHo) decreased progressively by exposure to 0 mM K solution. In 4 mM K solution, amiloride (1 mM), an inhibitor of Na(+)-H+ exchange, induced a reversible decrease in both aiNa and pHi, and an increase in pHs. Changes in pHi and pHs induced by application of amiloride in 0 mM K solution were larger than those in 4 mM K solution. The rate of decrease in pHi induced by amiloride became larger at longer exposure to 0 mM K solution. Lowering pHo from 7.4 to 6.4 induced a larger decrease in pHi in 0 mM K solution than that in 4 mM K solution. Lowering pHo from 7.4 to 5.4 reversed the difference between pHs and pHo. These results suggest that in guinea-pig papillary muscle, Na(+)-H+ exchange is active to regulate intracellular H+ under resting condition and under intracellular acidic condition, H+ extrusion via the Na(+)-H+ exchange would be accelerated not only by the net thermodynamic driving force for Na+ and H+ but also by other factors.

Intralenticular Na⁺ and rat lens H⁺ activities (aNa and pH_i, respectively) were measured in vitro at the posterior cortical layers of lens fibers using ion-selective microelectrodes. In control HCO₃–-free solution (K⁺: 5 mM; external pH (pH_o): 7.3), intralenticular potential (V_m) was ––61.5 ± 2.4 mV, aNa was 19.4 ± 4.6 mMand pH_i was 6.90 ± 0.06 (mean ± SD). In O-mM K⁺ solution, Vm slightly depolarized, but aNa and pH_i did not change. Increasing K⁺ concentration to 35 mM induced a large depolarization of V_m, associated with a reduction in aNa and an increase in pH_i. pH_i was decreased by lowering pH_o, but internal acidification thus induced did not show a complete recovery upon reintroduction of a normal solution. The pH_i was immediately increased by superfusion with a solution containing 20 mM NH₄Cl, and subsequent removal of NH₄Cl led to a sustained decrease in pH_i. Ouabain and amiloride (a blocker of Na⁺-H⁺ exchanger) did not exert any effects on aNa or on pH_i in normal solution at pH_o 7.3. Amiloride applied after the removal of NH₄Cl did not alter pH_i. These results provide evidence that aNa and pH_i at the posterior cortical fiber layers of the rat lens are influenced by V_m, and that, depending on the value of V_m, passive movements of Na₊ and H₊ can exert direct local effects on pH_i and aNa.

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