Phantom rivers filter birds and bats by acoustic niche.

Natural sensory environments, despite strong potential for structuring systems, have been neglected in ecological theory. Here, we test the hypothesis that intense natural acoustic environments shape animal distributions and behavior by broadcasting whitewater river noise in montane riparian zones for two summers. Additionally, we use spectrally-altered river noise to explicitly test the effects of masking as a mechanism driving patterns. Using data from abundance and activity surveys across 60 locations, over two full breeding seasons, we find that both birds and bats avoid areas with high sound levels, while birds avoid frequencies that overlap with birdsong, and bats avoid higher frequencies more generally. We place 720 clay caterpillars in willows, and find that intense sound levels decrease foraging behavior in birds. For bats, we deploy foraging tests across 144 nights, consisting of robotic insect-wing mimics, and speakers broadcasting bat prey sounds, and find that bats appear to switch hunting strategies from passive listening to aerial hawking as sound levels increase. Natural acoustic environments are an underappreciated niche axis, a conclusion that serves to escalate the urgency of mitigating human-created noise.

Live volumetric (4D) visualization and guidance of in vivo human ophthalmic surgery with intraoperative optical coherence tomography.

Minimally-invasive microsurgery has resulted in improved outcomes for patients. However, operating through a microscope limits depth perception and fixes the visual perspective, which result in a steep learning curve to achieve microsurgical proficiency. We introduce a surgical imaging system employing four-dimensional (live volumetric imaging through time) microscope-integrated optical coherence tomography (4D MIOCT) capable of imaging at up to 10 volumes per second to visualize human microsurgery. A custom stereoscopic heads-up display provides real-time interactive volumetric feedback to the surgeon. We report that 4D MIOCT enhanced suturing accuracy and control of instrument positioning in mock surgical trials involving 17 ophthalmic surgeons. Additionally, 4D MIOCT imaging was performed in 48 human eye surgeries and was demonstrated to successfully visualize the pathology of interest in concordance with preoperative diagnosis in 93% of retinal surgeries and the surgical site of interest in 100% of anterior segment surgeries. In vivo 4D MIOCT imaging revealed sub-surface pathologic structures and instrument-induced lesions that were invisible through the operating microscope during standard surgical maneuvers. In select cases, 4D MIOCT guidance was necessary to resolve such lesions and prevent post-operative complications. Our novel surgical visualization platform achieves surgeon-interactive 4D visualization of live surgery which could expand the surgeon's capabilities.

A comparison of two biomaterial carriers for osteogenic protein-1 (BMP-7) in an ovine critical defect model.

Critical size defects in ovine tibiae, stabilised with intramedullary interlocking nails, were used to assess whether the addition of carboxymethylcellulose to the standard osteogenic protein-1 (OP-1/BMP-7) implant would affect the implant's efficacy for bone regeneration. The biomaterial carriers were a 'putty' carrier of carboxymethylcellulose and bovine-derived type-I collagen (OPP) or the standard with collagen alone (OPC). These two treatments were also compared to "ungrafted" negative controls. Efficacy of regeneration was determined using radiological, biomechanical and histological evaluations after four months of healing. The defects, filled with OPP and OPC, demonstrated radiodense material spanning the defect after one month of healing, with radiographic evidence of recorticalisation and remodelling by two months. The OPP and OPC treatment groups had equivalent structural and material properties that were significantly greater than those in the ungrafted controls. The structural properties of the OPP- and OPC-treated limbs were equivalent to those of the contralateral untreated limb (p > 0.05), yet material properties were inferior (p < 0.05). Histopathology revealed no residual inflammatory response to the biomaterial carriers or OP-1. The OPP- and OPC-treated animals had 60% to 85% lamellar bone within the defect, and less than 25% of the regenerate was composed of fibrous tissue. The defects in the untreated control animals contained less than 40% lamellar bone and more than 60% was fibrous tissue, creating full cortical thickness defects. In our studies carboxymethylcellulose did not adversely affect the capacity of the standard OP-1 implant for regenerating bone.

Apolipoprotein E allele-dependent pathogenesis: a model for age-related retinal degeneration.

Age-related macular degeneration (AMD) is a late-onset, multifactorial, neurodegenerative disease of the retina and the leading cause of irreversible vision loss in the elderly in the Western world. We describe here a murine model that combines three known AMD risk factors: advanced age, high fat cholesterol-rich (HF-C) diet, and apolipoprotein E (apoE) genotype. Eyes of aged, targeted replacement mice expressing human apoE2, apoE3, or apoE4 and maintained on a HF-C diet show apoE isoform-dependent pathologies of differential severity. ApoE4 mice are the most severely affected. They develop a constellation of changes that mimic the pathology associated with human AMD. These alterations include diffuse sub-retinal pigment epithelial deposits, drusenoid deposits, thickened Bruch's membrane, and atrophy, hypopigmentation, and hyperpigmentation of the retinal pigment epithelium. In extreme cases, apoE4 mice also develop marked choroidal neovascularization, a hallmark of exudative AMD. Neither age nor HF-C diet alone is sufficient to elicit these changes. We document choroidal neovascularization and other AMD-like ocular pathologies in an animal model that exploits known AMD risk factors. The model is additionally attractive because it is not complicated by invasive experimental intervention. Our findings in this model implicate the human apoE E4 allele as a susceptibility gene for AMD and support the hypothesis that common pathogenic mechanisms may underlie AMD and Alzheimer's disease.

Dietary-induced metabolic acidosis decreases bone mineral density in mature ovariectomized ewes.

Dietary-induced metabolic acidosis (DIMA) may be a significant confounder in the development of osteoporosis. Diets that are acidifying are typically rich in proteins and grains and relatively poor in fruits and vegetables. Previous studies have not examined whether an interaction between estrogen depletion and DIMA have a compounded affect on bone mineral density loss. Sheep have been used successfully in previous studies to examine the interaction of bone turnover and ovariectomy. Therefore, the goal of this pilot study was to determine if bone mineral density (BMD) loss could be induced using DIMA in skeletally mature ovariectomized (OVX) ewes.

Retinal pigment epithelial tear with vitreomacular attachment: a novel pathogenic feature.

BACKGROUND: The development of tears of the retinal pigment epithelium (RPE) has classically been described with or without choroidal neovascularization (CNV) or after laser treatment. Tangential shear forces within the RPE or CNV are usually considered to cause the dehiscence. METHODS: Three patients with CNV and spontaneous RPE tear and additional vitreomacular traction were examined by fluorescein angiography (FA), optical coherence tomography (OCT) and kinetic ultrasound. RESULTS: From the pre-tear to the tear stage a sudden decrease in vision was observed. Fluorescein angiographic images demonstrated RPE-tear formation with blocked filling in the area of the contracted RPE and a well-demarcated hyperfluorescence in the bed of the torn RPE. OCT-scans demonstrated vitreomacular traction at the foveal area in all three cases. Kinetic ultrasound revealed vitreous attachments at the optic disc and fovea. CONCLUSION: Magnitude, variation of mechanical forces, and the continuous shear stress of the aged vitreous gel transmitted across vitreoretinal attachments may cause a chronic stimulus to retina and RPE. Vitreomacular traction may contribute to the subsequent formation of RPE tears via mechanical or cell mediator pathways.

In-vivo response to free electron laser incision of the rabbit cornea.

BACKGROUND AND OBJECTIVE: We analyzed the in vivo ocular response to corneal incisions made by Medical Free Electron Laser (MFEL) as a function of scan rate and incision depth. Additionally, we compared biomicroscopy, optical coherence tomography (OCT), and light microscopy as ocular response diagnostic tools. STUDY DESIGN/MATERIALS AND METHODS: Rabbit corneas were incised with pulsed MFEL radiation at 2.94 microm wavelength, scalpel incisions or focal cautery treatment were used as controls. The MFEL beam scan rate ranged from 0.2 to 1.0 mm/second. Ocular effects were monitored for 2 hours postoperatively using OCT and slit lamp examination. Ocular tissue was fixed for light microscopic examination. RESULTS: Anterior chamber fibrin formation correlated with MFEL incision depth. Slower scan rates resulted in deeper incisions and greater fibrin formation. OCT was better than slit lamp biomicroscopy at identifying fibrin attachments. OCT and light microscopy proved to be excellent companion technologies. CONCLUSIONS: Deep corneal incisions in the rabbit produced by the MFEL resulted in fibrin formation in the anterior chamber.

Macular translocation with 360-degree peripheral retinectomy impact of technique and surgical experience on visual outcomes.

PURPOSE: To evaluate the impact of technique and surgical experience on complications and outcomes of macular translocation surgery with 360-degree peripheral retinectomy (MTS360). METHODS: Twenty-six consecutive patients underwent MTS360 in a prospective study of macular translocation surgery for subfoveal choroidal neovascularization (CNV) in eyes with age-related macular degeneration (ARMD). Data gathered included intraoperative and postoperative events and pre- and postoperative standardized visual acuity recorded as number of letters read. Because the surgical technique changed particularly during the first 16 cases, patients were grouped into an evolving treatment group of the first 16 patients (Group 1) and a modified treatment group of the final 10 patients (Group 2). RESULTS: As techniques evolved in this series, ease of surgery increased. There were significant decreases in surgery duration and in number of retinotomies required to induce artificial retinal detachment. Number of postoperative retinal detachments decreased from five in Group 1 to none in Group 2. Change in visual acuity was significantly different between the two groups: Group 1 had an average loss of 14 letters (<3 lines) and Group 2 an average gain of 3 letters (<1 line) (P < 0.05). Average postoperative visual acuity was significantly better for Group 2 (68 letters, approximately 20/80) than for Group 1 (47 letters, approximately 20/250) (P < 0.01). CONCLUSION: Surgical experience and a progressively modified surgical technique decreased perioperative complications and improved visual outcomes after MTS360. With modified MTS360, central vision has been salvaged for almost 1 year of follow-up in patients presenting with vision loss from subfoveal CNV and ARMD.

Successful macular translocation with temporary scleral infolding using absorbable sture.

PURPOSE: To describe successful macular translocation with temporary scleral infolding in a series of patients with small subfoveal choroidal neovascularization due to age-related macular degeneration or ocular histoplasmosis syndrome. METHODS: Ten eyes of 10 consecutive patients were studied in a prospective, nonrandomized clinical trial. Macular translocation with scleral infolding (MTSI) was performed. Absorbable polyglactin suture was used to create temporary scleral infolding. Distance and stability of retinal translocation, corneal topography, visual acuity, and rates of complications were measured. RESULTS: The median distance of translocation in the early postoperative period was 1,700 microm (range, 680-3,200) and did not regress after resolution of the scleral infolding. Induced postoperative oblique corneal astigmatism resolved, coinciding with the disappearance of peripheral retinal elevation due to scleral infolding. Three patients gained more than two lines of vision, two patients were within two lines of preoperative vision, and five patients lost more than two lines of vision. Complications were similar to previously published reports. CONCLUSION: Temporary scleral infolding is an effective technique in MTSI. The distance of translocation is comparable to that achieved with nonabsorbable suture or scleral resection, and does not regress after resolution of the scleral infolding. Induced postoperative corneal astigmatism appears to resolve.

Induced corneal astigmatism after macular translocation surgery with scleral infolding.

OBJECTIVE: To document the corneal astigmatism that occurs with macular translocation after scleral infolding surgery. DESIGN: Retrospective case series of a nonrandomized clinical trial. PARTICIPANTS: Eight consecutive age-related macular degeneration patients (eight eyes) with choroidal neovascularization who underwent macular translocation with scleral infolding at the Duke University Eye Center from December 1998 through October 1999. METHODS: We retrospectively reviewed the charts of eight consecutive patients who underwent macular translocation surgery involving scleral infolding in the superotemporal quadrant. Two patients subsequently underwent release of scleral infolding. MAIN OUTCOME MEASURES: After surgery, these eyes were evaluated for corneal astigmatism with manifest refraction, keratometry, and computerized corneal topography. RESULTS: All eight eyes of eight patients revealed marked degrees of corneal astigmatism. Measurement of astigmatism via manifest refraction, keratometry, and corneal topography confirmed postoperative astigmatism corresponding to the axis of the scleral infolding. The amount of corneal astigmatism ranged from 1.75 to 7.37 diopters (D; mean, 4.60 D), with steepening along the axis of scleral infolding in the superotemporal quadrant of each eye (mean, 42.50 degrees from vertical; range, 24 degrees -66 degrees from vertical). Release of scleral infolding in two patients resulted in significant reduction of corneal astigmatism. CONCLUSIONS: Scleral shortening procedures used in macular translocation surgery may induce large amounts of corneal astigmatism. These patients should be assessed with keratometry and corneal topography to determine the accurate amount and axis. Thereafter, contact lens fitting or scleral infolding release may be considered as therapeutic options for large amounts of astigmatism persisting after surgery.

Pars plana vitrectomy, subretinal injection of tissue plasminogen activator, and fluid-gas exchange for displacement of thick submacular hemorrhage in age-related macular degeneration.

PURPOSE: To evaluate a new procedure for displacement of large, thick submacular hemorrhage in patients with age-related macular degeneration. METHODS: Retrospective review of 11 eyes of 11 patients with age-related macular degeneration and thick submacular hemorrhage (defined as causing retinal elevation detectable on stereo fundus photographs) treated with vitrectomy, subretinal injection of tissue plasminogen activator (25 or 50 microg), and fluid-gas exchange with postoperative prone positioning. Outcome measures included displacement of hemorrhage from the fovea, best postoperative visual acuity, and final postoperative visual acuity. RESULTS: In the 11 affected eyes of 11 patients (seven men and four women; mean age, 76 years), preoperative visual acuity ranged from 20/200 to hand motions. With surgery, subretinal hemorrhage was displaced from the fovea in all 11 cases. Mean postoperative follow-up was 6.5 months (range, 1 to 15 months). Best postoperative visual acuity varied from 20/30 to 5/200, with improvement in nine (82%) cases and no change in two cases. Eight eyes (73%) measured 20/200 or better, with four of these eyes (36%) 20/80 or better. Final postoperative visual acuity ranged from 20/70 to light perception, with improvement in eight (73%) cases, no change in one case, and worsening in two cases. A statistically significant difference was found between preoperative and best postoperative visual acuity (P =.004) but not between preoperative and final visual acuity (P =.16). Hemorrhage recurred in three (27%) eyes, causing severe visual loss in one eye. CONCLUSIONS: This technique displaces submacular hemorrhage from the fovea and can improve vision in patients with age-related macular degeneration. However, recurrence of hemorrhage occurred in 27% of eyes and caused severe visual loss in one eye. A randomized, prospective clinical trial is necessary to determine the efficacy of this technique in comparison with other proposed treatments.

Macular translocation: unifying concepts, terminology, and classification.

PURPOSE: To describe some unifying concepts, terminology, and classification of macular translocation so as to facilitate communication within the scientific community. METHODS: A panel of ophthalmologists with expertise in macular translocation reviewed available data and developed some unifying concepts, terminology, and classification of macular translocation. RESULTS: Macular translocation may be defined as any surgery that has a primary goal of relocating the central neurosensory retina or fovea intraoperatively or postoperatively specifically for the management of macular disease. It may be classified according to the size of the retinotomy and, where applicable, the technique of chorioscleral shortening used. The direction of macular translocation is denoted by the movement of the neurosensory macula relative to the underlying tissues. Effective macular translocation may be defined as successful intraoperative or postoperative relocation of the fovea overlying a subfoveal lesion to an area outside the border of the lesion. The concepts of minimum desired translocation and median postoperative foveal displacement can give some useful idea of the likelihood of effective macular translocation before surgery. CONCLUSIONS: Use of a common standardized terminology for macular translocation will facilitate communication within the scientific community and enhance further research in this area. However, the definitions, terms, classification, and concepts concerning macular translocation are likely to continue to evolve as macular translocation undergoes further modifications and refinements.

Macular translocation with radial scleral ouffolding: experimental studies and initial human results.

PURPOSE: Different techniques have been proposed for translocating the macula in patients with subfoveal neovascularization secondary to age-related macular degeneration. A new approach utilizing radial outfolding of the sclera was investigated. MATERIALS AND METHODS: Surgical techniques and retinal displacement were evaluated in animal trials using metal scleral clips. Successful translocation and reattachment of the retina was achieved in eight rabbits (eight eyes). We conducted a retrospective review of macular translocation surgery, performed with radial scleral outfolding, in a series of five consecutive human patients (five eyes) using full-thickness transscleral mattress sutures. RESULTS: After surgery, vision improved in two of five patients, with one patient achieving a visual acuity of 20/50. The mean angle of rotation was 11.5 deg (range 8.6 -15.1). The mean amount of foveal displacement was 1,276 pm (range 852-1,620). Complications included one case of retinal detachment, one of diplopia, and one of subretinal hemorrhage. CONCLUSIONS: Limited macular translocation by radial scleral outfolding can improve vision in selected patients. Radial evagination appears to be as effective as circumferential infolding.

Comparison of macular versus paramacular retinal sensitivity to femtosecond laser pulses.

Single 130 fs laser pulses in the near-IR (800 nm) were used to create ophthalmoscopically viewed minimum visible lesions (MVLs) within the macular and paramacular regions in rhesus monkey eyes. MVL thresholds at 1 and 24 h are reported as the 50% probability for damage (ED50) together with their fiducial limits at the 95% confidence level. These measured thresholds are compared with previously reported thresholds for near-IR and visible wavelengths for both macular and paramacular areas. Threshold doses were lower at the 24 h reading than at the 1 h reading for both retinal regions and the ED50s for the macula were slightly lower than for the paramacula. We measured the 24 h MVL ED50 thresholds to be 0.35 and 0.55 microJ for the macular and paramacular areas, respectively. The combined data for both areas yielded a threshold of 0.45 microJ.

Features of macular hole closure in the early postoperative period using optical coherence tomography.

PURPOSE: Studying the retina in the early postoperative period after macular hole surgery is difficult because of the limitation of imaging of the fundus through a gas tamponade. Silicone oil was shown recently to be an effective alternative to gas for macular hole repair. The authors hypothesized that optical coherence tomography (OCT) could be performed through silicone oil to study early macular hole closure. METHODS: Fourteen patients with idiopathic full-thickness macular holes underwent repair, including vitrectomy and silicone fill of the vitreous cavity. Silicone oil was removed 5 to 18 weeks later in a second operative procedure. Optical coherence tomography images were obtained preoperatively (n = 14), on the first postoperative day (n = 7), after 1 week (n = 4), after 1 month (n = 14), and after silicone oil removal (n = 14). RESULTS: By the first postoperative day, the retina was flat and the hole was open or closed in all patients. By 1 month, 9 of 14 patients had flat retinas and closed holes, whereas the other 5 patients had flat retinas and open holes. All patients who had an open hole after 1 month had a reopening of the hole after silicone oil removal. CONCLUSIONS: Flattening of the retina with resolution of the foveal cysts after macular hole repair occurs by the first postoperative day. Closure of the horizontal retinal separation is variable but occurs by the first postoperative month in cases of successful macular hole repair. Persistent retinal separation after 1 month may be predictive of hole reopening.

Combined superior oblique muscle recession and inferior oblique muscle advancement and transposition for cyclotorsion associated with macular translocation surgery.

PURPOSE: The purpose of this study was to evaluate the effects of oblique muscle surgery on the large-angle incyclotorsion resulting from macular translocation surgery for severe age-related macular degeneration. METHODS: Patients undergoing macular translocation (superiorly) at our institution from May 1996 until November 1998 were included. In the Staged Group, strabismus surgery for symptomatic incyclotorsion was performed after the macular translocation, and in the Combined Group, it was performed simultaneous with the macular translocation. Cyclotorsion was quantified using Maddox rod testing. Surgery for incyclotorsion included superior oblique muscle recession combined with inferior oblique muscle advancement and transposition in the affected eyes. The minimum follow-up time was 6 weeks. RESULTS: Fifteen patients (15 eyes) were included (ages 66-89 years). Nine eyes (Baseline Group) had macular translocation surgery before any strabismus surgery; the mean postoperative incylotorsional angle was 33.4 +/- 18.3 degrees (range, 20-80 degrees) after a mean follow-up of 6.6 months. Four of these eyes (Staged Group) underwent oblique muscle surgery for symptomatic incyclotorsion, which reduced the mean incyclotorsion from 26.9 +/- 6.9 degrees (range, 20-35 degrees) to 9. 9 +/- 7.9 degrees (range, 2.5-20 degrees)-a mean reduction of 16.9 +/- 1.3 degrees (P =.00012), after a mean follow-up of 4.6 months. Six additional eyes (Combined Group) had simultaneous macular translocation and oblique muscle surgery, with a mean postoperative cyclotorsional angle of 14.0 +/- 6.7 degrees (range, 4-22.5 degrees), after a mean follow-up of 3.75 months. CONCLUSION: Oblique muscle surgery is effective at reducing the large degree of incyclotorsion resulting from macular translocation surgery and may be used either following or simultaneous with retinal surgery.

Diagnosis of vitreoretinal adhesions in macular disease with optical coherence tomography.

PURPOSE: To compare the relative incidence of vitreoretinal adhesions associated with partial vitreous separation within the macula diagnosed with optical coherence tomography (OCT) with that of those diagnosed with biomicroscopy. METHODS: The authors obtained linear cross-sectional retinal images using OCT in patients with selected macular diseases. Additional studies included biomicroscopy, fundus photography, fluorescein angiography, and B-scan ultrasonography. RESULTS: Optical coherence tomography was performed on 132 eyes of 119 patients. Vitreoretinal adhesions within the macula were identified using OCT in 39 eyes (30%) with the following diagnoses: idiopathic epiretinal membrane (n = 13), diabetic retinopathy (n = 7), idiopathic macular hole (n = 7), cystoid macular edema (n = 7), and vitreomacular traction syndrome (n = 5). Biomicroscopy identified vitreoretinal adhesions in only 11 eyes (8%). Two distinct vitreoretinal adhesion patterns were identified with OCT, each associated with partial separation of the posterior hyaloid face: focal (n = 25) and multifocal (n = 14). CONCLUSIONS: Optical coherence tomography is more sensitive than biomicroscopy in identifying vitreoretinal adhesions associated with macular disease.

Electron immunocytochemical analysis of posterior hyaloid associated with diabetic macular edema.

BACKGROUND: Tangential traction in the macula from a thickened posterior hyaloid of the vitreous has been implicated as a cause of diffuse diabetic macular edema. Vitrectomy with peeling of the posterior hyaloid has been shown to reduce retinovascular leakage and improve vision in select patients. We report a clinicopathologic correlation using electron microscopy and electron immunocytochemistry to characterize the membrane infiltrating the posterior hyaloid in two such patients. METHODS: Two patients presented with vision loss associated with diffuse diabetic macular edema and an attached, thickened, and taut posterior hyaloid. The patients underwent vitrectomy with peeling of the posterior hyaloid. The premacular posterior hyaloid specimens then were analyzed by electron microscopy with immunocytochemical staining for cytokeratin and glial fibrillary acidic protein. RESULTS: Both posterior hyaloid specimens contained collagen and a large cellular component. Immunogold labeling showed cells positive for glial fibrillary acidic protein or cytokeratin. With double labeling, no cells expressed both proteins simultaneously. Clinically, both patients had vision improvement and macular edema resolution after surgery. CONCLUSIONS: The thickened, taut posterior hyaloid observed in our patients with diabetic macular edema contained cells of glial and epithelial origin. This cellular infiltration may contribute to abnormal vitreomacular adherence and could play a role in the pathogenesis of macular edema in some patients with diabetes.

Thresholds for visible lesions in the primate eye produced by ultrashort near-infrared laser pulses.

PURPOSE: To evaluate the effects of near-infrared (near-IR) ultrashort laser pulses on the retinas of rhesus monkey eyes and to perform threshold measurements for minimum visible lesions (MVLs) at pulse widths ranging from nanoseconds to femtoseconds. METHODS: Near-infrared single laser pulses were placed within the macular area of live rhesus monkey eyes for five different pulse widths (7 nsec; 80, 20, and 1 psec; and 150 fsec). One visible wavelength of 530 nm at 100 fsec was also included in the study. Visible lesion thresholds (MVL-ED50) were determined 1 hour and 24 hours after exposure. Fluorescein angiography thresholds (FAVL-ED50) were also determined using a probit analysis of the dosage. Thresholds were calculated as that dosage causing a 50% probability for damage, and the fiducial limits were calculated at the 95% confidence level. RESULTS: For all pulse widths, the 24-hour MVL-ED50 was lower than the 1-hour MVL-ED50, and they both decreased with decreasing pulse width. Thresholds at the 1-hour reading decreased from 28.7 microJ at 7 nsec to 1.8 microJ at 150 fsec, whereas thresholds at 24 hours decreased from 19.1 microJ at 7 nsec to 1.0 microJ at 150 fsec. The doubled 1060-nm wavelength of the 530-nm threshold decreased from 0.36 to 0.16 microJ after 24 hours. FAVL-ED50s were much higher than MVL-ED50s, showing that FA was not as sensitive in determining damage levels. CONCLUSIONS: Laser pulse widths less than 1 nsec in the near-IR are capable of producing visible lesions in rhesus monkey eyes with pulse energies between 5 and 1 microJ. Also, the near-IR thresholds for these pulse widths are much higher than for the visible wavelengths. As with visible wavelengths, FA is not as sensitive in determining threshold levels as is visually observing the retina through a fundus camera.

Ultrashort laser pulse bioeffects and safety.

Recent studies of retinal damage due to ultrashort laser pulses have shown that less energy is required for retinal damage for pulses shorter than 1 ns than that for longer pulses. It has also been shown that more energy is required for near-infrared (NIR) wavelengths than in the visible because the light focuses behind the retina, requiring more energy to produce a damaging fluence on the retina. We review the progress made in determining the trends in retinal damage from laser pulses of 1 ns to 100 fs in the visible and NIR wavelength regimes. We have determined the most likely damage mechanism(s) operative in this pulse width regime.