Atropine sulfate

Recordings were conducted at preinjection and then, at postinjection time points of 7 to 8, 15 to 16, 29 to 38, and 51 to 64 wk after vector delivery. Pupils were dilated with topical atropine sulfate 1% (Akorn, Inc.), tropicamide 1% (Akorn, Inc.), and phenylephrine 10% (Paragon Biotech). After induction with intravenous propofol (Zoetis), dogs were maintained under general inhalation anesthesia (isoflurane 2 to 3%; Akorn, Inc.). Full-field flash ERG was performed on both eyes using a custom-built Ganzfeld dome fitted with light-emitting diode stimuli from a ColorDome stimulator (Diagnosys LLC). After 20 min of dark adaptation, rod and mixed rod–cone-mediated responses to single 4-ms white flash stimuli of increasing intensities (−3.7 to 0.5 log cd⋅s⋅m⁻²) were recorded. After 5 min of white light adaptation (10.6 cd⋅m⁻²), cone-mediated responses to a series of single white flashes (−2.7 to 0.5 log cd⋅s⋅m⁻²) and to 29.4-Hz flicker stimuli (−2.7 to 0.2 log cd⋅s⋅m⁻²) were recorded. Finally, photopic long-flash ERGs were recorded using 200-ms white stimuli of 400 cd.m⁻² on a rod-suppressing white background of 10.6 cd.m⁻² to assess the ON and OFF pathways. Statistical significance was calculated by an unpaired t test using GraphPad (GraphPad Software).

In addition to being dark reared, mice were maintained in darkness for at least 16 hours before and during the MRI examination. In all groups, immediately before the MRI experiment, animals were anesthetized with urethane (36% solution intraperitoneally; 0.083 mL/20 g animal weight, prepared fresh daily; Sigma-Aldrich Corp.) and treated topically with 1% atropine sulfate (Akorn Pharmaceuticals, Lake Forest, IL, USA) to ensure dilation of the pupil. This was followed by application of 3.5% lidocaine gel (Akorn Pharmaceuticals) to reduce sensation that might trigger eye motion and to help keep the ocular surface moist. High resolution 1/T1 data were acquired on a 7 Tesla system (ClinScan; Bruker, Billerica, MA, USA) by using a receive-only surface coil (1.0-cm diameter), as regularly performed in our laboratory.^{26 (link)} In all cases, several single spin-echo (time to echo [TE] 13 milliseconds, 7 × 7 mm², matrix size 160 × 320, slice thickness 600 μm, in-plane resolution 21.875 μm) images were acquired at different repetition times (TRs) in the following order (number per time between repetitions in parentheses): 0.15 seconds (6), 3.50 seconds (1), 1.00 seconds (2), 1.90 seconds (1), 0.35 seconds (4), 2.70 seconds (1), 0.25 seconds (5), and 0.50 seconds (3). To compensate for reduced signal-noise ratios at shorter TRs, progressively more images were collected as the TR decreased.