Michael R. Petersen

Perception of Conspecific Vocalizations by Japanese Macaques

Japanese macaques (Macaca fuscata) and control species (vervet, pigtailed macaque, bonnet macaque) were trained for food to respond to one class of recorded fuscata vocalizations an

Auditory thresholds and kanamycin‐induced hearing loss in the guinea pig assessed by a positive reinforcement procedure

Absolute thresholds from 125 Hz to 52 kHz are determined for six guinea pigs trained by a positive reinforcement method. Four to five hundred trials were conducted during daily testing sessions and little between- or within-subject variability was found. Two of the six animals were subsequently treated with kanamycin and the development of a hearing loss for the high frequencies was followed. Loss of outer and to a lesser extent inner hair cells was well correlated with the threshold shift observed. Contrary to the experience of previous investigators, this operant training procedure has proved as efficient as that for other species of experimental animals, such as the monkey and the chinchilla. It holds excellent promise for future auditory behavioral work with the guinea pig.

Outcomes Of Transconjunctival Sutureless 25-gauge Vitrectomy With Silicone Oil Infusion

Purpose: To evaluate the outcomes and complications of surgical management with 25-gauge pars plana vitrectomy (PPV) and silicone oil (SO) tamponade in complex vitreoretinal diseases. Methods: Retrospective review of a consecutive, interventional case series at a single center. Results: Thirty-five eyes of 35 patients were included in the study. The indications for vitrectomy included tractional retinal detachment (11 eyes), macular hole (6 eyes), proliferative vitreoretinopathy or recurrent retinal detachment (9 eyes), neovascular glaucoma (3 eyes), giant retinal tear (3 eyes), and pathologic myopia with epiretinal membrane or macular hole (3 eyes). All patients underwent 25-gauge PPV with either 1,000-centistoke (n = 31) or 5,000-centistoke (n = 4) SO tamponade infused through a 24-gauge angiocatheter. No intraoperative complications were noted. The median preoperative visual acuity was counting fingers (range, 20/50 to light perception). The median postoperative visual acuity after a median follow-up of 6 months (range, 1–19 months) was 20/200 (range, 20/30 to light perception). A small subconjunctival SO bleb was identified in two patients. Recurrent retinal detachment occurred in three patients. No significant complications relating to the use of SO in the setting of 25-gauge PPV occurred. Conclusions: Advances in 25-gauge PPV instrumentation have enabled expanding indications for 25-gauge PPV. 25-Gauge PPV with SO tamponade is safe and efficient and can be considered in the surgical management of complex vitreoretinal disease.

PRIMARY REPAIR OF RETINAL DETACHMENT WITH 25-GAUGE PARS PLANA VITRECTOMY

Purpose: To evaluate 25-gauge pars plana vitrectomy (PPV) for primary repair of rhegmatogenous retinal detachment (RRD). Study Design and Participants: This retrospective, consecutive case series included 42 eyes of 41 patients who underwent primary repair of RRD utilizing transconjunctival 25-gauge PPV without scleral buckling at the Cincinnati Eye Institute from July 2004 through January 2007. Methods: The medical records were retrospectively reviewed, and the corresponding demographic data, preoperative ophthalmic diagnoses, surgical management, and postoperative course and treatment were recorded. Main outcome measures included single surgery anatomical success, preoperative and postoperative visual acuity, and complications. Results: Most patients had pseudophakic RRD (36 [85.7%] of 42 eyes). The crystalline lens was present in the remaining 6 eyes (14.3%). Of 42 eyes, 28 (66.7%) had macula-on RRD, while 14 (33.3%) had macula-off RRD. Four surgeons contributed to this study, and 25-gauge PPV instrumentation, a wide-angle viewing system, endolaser photocoagulation, and gas tamponade were used in each case. The single surgery anatomical success rate was 92.9% (39 of 42 eyes). For eyes with macula-on RRD, best-corrected visual acuity was 20/50 (0.43 logMAR [logarithm of the minimum angle of resolution]) preoperatively and 20/30 (0.23 logMAR) postoperatively (P = 0.24). For eyes with macula-off RRD, best-corrected visual acuity was 5/200 (1.56 logMAR) preoperatively and 20/30 (0.23 logMAR) postoperatively (P = 0.001). Three eyes required additional surgery for final reattachment. Final reattachment was achieved in 100% of patients (mean follow-up, 8 months). Conclusions: Twenty-five–gauge PPV with laser retinopexy and gas tamponade is effective for primary repair of RRD. The single operation anatomical success rate is comparable with rates reported for primary vitrectomy with 20-gauge instrumentation, scleral buckling, and combined vitrectomy/scleral buckling.

Ocular Vascular Thrombotic Events: Central Retinal Vein and Central Retinal Artery Occlusions

We prospectively assessed associations of thrombophilia— hypofibrinolysis with central retinal vein occlusion (CRVO) (40 patients) and central retinal artery occlusion (CRAO) (9 patients). We used polymerase chain reaction measures for thrombophilia (factor V Leiden, prothrombin, C677T MTHFR, platelet glycoprotein PlA1/A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). Serologic thrombophilia measures included protein C, protein S (total and free) and antithrombin III, homocysteine, lupus anticoagulant, anticardiolipin antibodies IgG-IgM, and factors VIII and XI. Serologic hypofibrinolysis measures included Lp(a) and plasminogen activator inhibitor activity. For comparison with 40 CRVO and 9 CRAO patients, 80 and 45 race—gender matched controls were studied. The factor V mutation was more common in CRVO (3/40, 8%) than controls (0/79, 0%), P = .036, as was high (>150%) factor VIII (12/40, 30%) versus (4/77, 5%), P = .0002. Low antithrombin III (<80%) was more common in CRVO (5/39, 13%) than in controls (2/73, 3%), P = .049. Homocysteine was high (≥13.5 µmol/L) in 5/39 (13%) CRVO patients versus 2/78 controls (3%), P = .04. Three of 9 CRAO patients (33%) had low (<73%) protein C versus 2/37 controls (5%), P = .044. Two of 9 CRAO patients (22%) had high (≥13.5 µmol/L) homocysteine versus 0/42 controls (0%), P =. 028. Four of 9 CRAO patients had the lupus anticoagulant (44%) versus 4/33 (12%) controls (P = .050). CRVO is associated with familial thrombophilia (factor V Leiden, factor VIII, low antithrombin III, homocysteinemia), and CRAO is associated with familial and acquired thrombophilia (low protein C, homocysteinemia, lupus anticoagulant), providing avenues for thromboprophylaxis, and triggering family screening.

Progression of Diabetic Retionopathy after Pancreas Transplantation

The progression of diabetic retinopathy after combined pancreatic and kidney transplantation was studied in eight patients for 12 to 49 months. Four patients who had rapid pancreatic graft failure constituted a control group for comparison with four patients who retained functioning grafts. Using Fishers exact probability test, the authors found no posttransplantation difference between the two groups in visual acuity lost, severity of diabetic macular edema, extent of capillary closure, progression of preretinal gliosis, development of disc or preretinal neovascularization, or worsening of the severity of the retinopathy. Achievement of normoglycemia by pancreatic transplantation is not effective in halting the progression of diabetic retinopathy in patients who already have severe diabetic microangiopathy joined the current follow-up.

Auditory duration discrimination in Old World monkeys (Macaca, Cercopithecus) and humans

Auditory duration DLs at 2.0 kHz were measured in Old World monkeys (Macaca, Cercopithecus) and humans using a go, no-go repeating standard AX procedure and positive reinforcement operant conditioning techniques. For a 200-ms standard, monkey DLs were 45-125 ms, compared to 15-27 ms for humans. Weber fractions (delta T/T) for all species were smallest at standard durations of 200-400 ms and increased as standard duration decreased to 25 ms. Varying intensity from 30-70 dB SPL had only minor effects on DLs, except at the lowest levels tested, where DLs were elevated slightly. Monkeys had difficulty discriminating duration decrements, in contrast to humans. Results are discussed in relation to other comparative psychoacoustic data and primate vocal communication, including human speech.

Boston type 1 keratoprosthesis combined with silicone oil for treatment of hypotony in prephthisical eyes.

Purpose: To present the outcomes of Boston type I keratoprosthesis (KPro) implantation in combination with pars plana vitrectomy (PPV) and silicone oil for the treatment of hypotony in prephthisical eyes. Methods: Interventional case series. Thirteen eyes of 13 patients underwent Boston type I KPro implantation, pars plana vitrectomy, and silicone oil placement. Concurrent retinal detachment repair, membrane peel, or intraocular lens explantation were performed if necessary. Inclusion criteria for surgery were eyes with visual acuity worse than 20/400, previous failed penetrating keratoplasty, corneal opacification, visually significant or worsening hypotony, and visual acuity 20/200 or worse in the fellow eye. Outcome measures included Snellen best-corrected visual acuity, anatomic retinal attachment, and complications. Results: At the final follow-up (mean, 24 months; range, 5-66 months), visual acuity was improved in 10 of 13 eyes (77%), stable in 2 of 13 eyes (15%), and decreased in 1 of 13 eyes (8%). All eyes had attached retina with no progression to phthisis bulbi. No intraoperative complications occurred. Postoperative complications included retroprosthetic membrane (7 of 13), KPro melt (1 of 13), KPro leak (1 of 13), KPro infection (1 of 13), vitreous hemorrhage (1 of 13), and retinal detachment (1 of 13). Conclusions: Boston type I KPro implantation in combination with pars plana vitrectomy and intraocular silicone oil fill can improve vision in most prephthisical eyes with hypotony. Structural findings can also improve.

Indocyanine green-assisted internal limiting membrane peeling for macular holes to stain or not to stain?

Indocyanine Green–Assisted Internal Limiting Membrane Peeling for Macular Holes To Stain or Not To Stain? The retinal internal limiting membrane (ILM) forms the structural boundary between the retina and the vitreous. It is derived primarily from, and rests upon, a sea of Müller cell footplates that separates it from the nerve fiber layer.1 As a basement membrane, the ILM can act as a scaffold that may permit cellular proliferation and transmit tractional forces directly to the inner retina. The ILM is frequently involved in disorders that affect the vitreomacular interface, including epiretinal membranes, vitreomacular traction, and macular holes.2–8 Although to our knowledge there have been no randomized, prospective, controlled clinical trials, most evidence suggests that retinal ILM peeling improves anatomical and visual outcomes after macular hole repair.9–24 Indeed, a meta-analysis of data for 1,654 eyes demonstrated that ILM peeling significantly increased the anatomical and functional success rates of macular hole surgery (P 0.0001).13 Surgical peeling of the ILM can be technically challenging even for experienced vitreoretinal surgeons primarily due to its inherent transparency. Indocyanine green (ICG) was first introduced for intraocular use in 1998 to facilitate visualization of the anterior capsule of the crystalline lens.25 Shortly thereafter, ICG-assisted ILM peeling was described in human cadaveric eyes, as well as intraoperatively for macular hole repair.26–28 ICG enhances visualization of the ILM, and most clinical studies have reported visual and anatomical success with the use of this technique.17,27–45 Indeed, the largest clinical series of ICG-assisted ILM peeling for primary macular hole closure reported an anatomical success rate of 98% and an improvement of 2 lines of Snellen visual acuity in 96% of 121 eyes. No eyes lost visual acuity, and no complications were identified as a result of ICG use.39 This study, however, was noncomparative and retrospective and did not formally evaluate visual fields. In addition, power calculations suggested that a sample size of 300 would be required to have a reasonable chance of detecting a significant adverse event if the rate of that event were 1%.39 ICG-assisted ILM peeling has become routine practice for a large number of vitreoretinal surgeons, with 42% of these surgeons using ICG for 90% of their primary macular hole operations.46,47 ICG staining has been promoted as useful for surgeons learning to peel the ILM. According to the 2003 survey of the American Society of Retinal Specialists, 52% of vitreoretinal surgeons now using ICG-assisted ILM peeling had not routinely attempted ILM peeling before the introduction of ICG.47 Furthermore, several studies have demonstrated that ICG-assisted ILM peeling is helpful in challenging cases such as traumatic, recurrent, and long-standing macular holes as well as macular hole surgery in severely myopic eyes even in the presence of retinal detachment.27,28,30,32,37,48,49 Despite widespread use of ICG-assisted ILM peeling and many favorable reports, it is important to note that some clinical studies have reported unfavorable functional outcomes and complications, such as visual field defects or retinal pigment epithelium (RPE) changes.50–55 Investigators have generally attributed complications and unfavorable outcomes to the use of ICG. They may be correct. Nevertheless, it is important to recall that unfavorable results and these same complications have been previously described as surgeons began to peel the ILM even before the introThe authors received no public or private financial support pertaining to the information reported in this article. Reprint requests: Andrea P. Da Mata, MD, Cincinnati Eye Institute, 10494 Montgomery Road, Cincinnati, OH 45242; e-mail: andreadamata@hotmail.com

Comparison of 20-, 23-, and 25-Gauge Pars Plana Vitrectomy in Pseudophakic Rhegmatogenous Retinal Detachment Repair

BACKGROUND AND OBJECTIVE To compare 20-, 23-, and 25-gauge pars plana vitrectomy (PPV) for repair of primary pseudophakic rhegmatogenous retinal detachment. PATIENTS AND METHODS One hundred eyes of 94 pseudophakic patients who underwent primary rhegmatogenous retinal detachment repair with 20-, 23-, or 25-gauge transconjunctival PPV without scleral buckling were included. The medical records were retrospectively reviewed and the corresponding demographic information, preoperative ophthalmic diagnoses, surgical management, and postoperative course and treatment were recorded. RESULTS Retinal detachment repair was performed by one of four surgeons. All eyes underwent primary vitrectomy using either 20-, 23-, or 25-gauge vitrectomy instruments, a wide-angle viewing system, endolaser photocoagulation, and gas or silicone oil tamponade. Single surgery anatomical success was 25 of 28 eyes (89.3%) for 20-gauge, 24 of 27 eyes (88.9%) for 23-gauge, and 42 of 45 eyes (93.3%) for 25-gauge PPV. There was no statistical difference in single operation success or final visual acuity results between the groups and 100% of patients achieved final reattachment. CONCLUSION Twenty-, 23-, and 25-gauge instruments are equally effective options for primary repair of pseudophakic rhegmatogenous retinal detachment.