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PURPOSE: The blue-light-hazard is the experimental finding that blue light is highly toxic to the retina (photic retinopathy), in brief abnormally intense exposures, including sungazing or vitreoretinal endoillumination. This term has been misused commercially to suggest, falsely, that ambient environmental light exposure causes phototoxicity to the retina, leading to age-related macular degeneration (AMD). We analyze clinical, epidemiological and biophysical data regarding blue-filtering optical chromophores. DESIGN: Multi-institutional perspective. METHODS: Analysis and integration of data regarding the blue-light-hazard and blue-blocking filters in ophthalmology and related disciplines. RESULTS: Large epidemiological studies show that blue-blocking intraocular lenses (IOLs) do not decrease AMD risk or progression. Blue-filtering lenses cannot reduce disability glare because image and glare illumination are decreased in the same proportion. Blue light essential for optimal rod and retinal ganglion photoreception is decreased by progressive age-related crystalline lens yellowing, pupillary miosis and rod and retinal ganglion photoreceptor degeneration. Healthful daily environmental blue light exposure decreases in older adults, especially women. Blue light is important in dim environments where inadequate illumination increases risk of falls and associated morbidities. CONCLUSIONS: The blue-light-hazard is misused as a marketing stratagem to alarm people into using spectacles and IOLs that restrict blue light. Blue light loss is permanent for pseudophakes with blue-blocking IOLs. Blue-light-hazard misrepresentation flourishes despite absence of proof that environmental light exposure or cataract surgery causes AMD or that IOL chromophores provide clinical protection. Blue-filtering chromophores suppress blue light critical for good mental and physical health and for optimal scotopic and mesopic vision.

PURPOSE To report the clinical and optical coherence tomography (OCT) findings of a patient with chronic central serous chorioretinopathy (cCSC) who developed a short-term bacillary layer detachment after photodynamic therapy. METHODS A 56-year-old man presented with metamorphopsia and 20/100 visual acuity in his right eye. He was diagnosed with active, chronic central serous chorioretinopathy based on clinical findings and multimodal imaging. His visual problems and retinal findings persisted for three months before he was treated with half-fluence, half-dose verteporfin photodynamic therapy. RESULTS The patient had a prominent decrease in his vision post-operatively. Two days after treatment, multimodal imaging showed a marked increase in exudation that merged preoperative neurosensory retinal detachments. A prominent subfoveal bacillary layer detachment was also present. The subretinal fluid and bacillary layer detachment resolved over the next eight weeks, with a return of visual acuity to its baseline level and normalization of retinal structures except for a small zone of subfoveal ellipsoid zone and interdigitation zone disruption. CONCLUSION Half-fluence, half-dose verteporfin photodynamic therapy caused a fulminant increase in subretinal fluid and an associated subfoveal bacillary layer detachment. We hypothesize that cCSC-related chorioretinal dysfunction contributed to the severe PDT-induced local inflammatory reaction that caused the patient's bacillary layer detachment. Hyperacute choroidal exudation too fulminant for containment in subretinal space extended into and exceeded photoreceptor inner segment tensile strength, cleaving the myoid layer and/or dissecting it from the ellipsoid layer. This finding broadens the causality spectrum of bacillary layer detachments and vision losses that can follow photodynamic therapy.

Nonconfocal ultra-widefield scanning laser ophthalmoscopes produce foveal polarization artifacts that require normal Henle layer structure and are suppressed by center-involving diabetic macular edema. Polarization sensitivity is insufficient for the artifacts to be reliable clinical screening biomarkers., Purpose: Bowtie-shaped polarization artifacts are often present in nonconfocal ultra-widefield scanning laser ophthalmoscope (SLO) images. We studied these artifacts and evaluated their potential value as clinical biomarkers in screening for center-involving diabetic macular edema (DME). Methods: We performed a retrospective, observational, cohort study on 78 diabetic adult patients (143 eyes) who had spectral domain optical coherence tomography and nonmydriatic nonconfocal ultra-widefield SLO testing on the same day. Scanning laser ophthalmoscope green-only (532 nm), red-only (635 nm), and composite pseudocolor (532 plus 635 nm) images were examined for the presence of a foveal bowtie polarization artifact. Results: Polarization artifacts were absent in all but one eye with center-involving DME (32 of 33 eyes). Polarization artifacts were also absent in many eyes without center-involving DME (49 of 110 eyes in pseudocolor images). As clinical biomarkers of center-involving DME, artifact absence has high specificity (99, 100, and 98% for green, red, and pseudocolor images, respectively) but poor sensitivity (49, 31, and 40% for green, red, and pseudocolor images, respectively). Conclusion: Foveal bowtie-shaped polarization artifacts occur routinely in nonconfocal ultra-widefield SLO images. Their presence indicates preserved foveal Henle fiber layer structure. Contemporary nonconfocal ultra-widefield SLO images lack the sensitivity for their bowtie artifacts to serve as reliable biomarkers in screening for center-involving DME.

Purpose Ultraviolet-B (UV-B) radiation can cause phototoxic macular injuries in young people who have been sunbathing but not sungazing and in welders. Welders have a reportedly increased risk of uveal melanoma. We analyze phakic and pseudophakic risks for solar and welding arc UV-B exposure. Design Optical radiation measurement, analysis, and perspective. Methods Spectral transmittances were measured for UV-transmitting, UV-blocking, and blue-blocking intraocular lenses (IOLs). The photoprotective performances of crystalline and intraocular lenses were analyzed using relevant epidemiologic and laboratory data and action spectra for acute retinal phototoxicity and melanoma photocarcinogenesis. Results Crystalline lens UV-B retinal protection is deficient in children and young adults, increasing their potential susceptibility to acute retinal phototoxicity and hypothetical photomelanomagenesis. UV-B radiation has sufficient energy/photon to induce primary melanomagenic DNA lesions, unlike blue light or UV-A radiation. UV-blocking and blue-blocking IOLs have negligible UV-B transmittance. UV-transmitting IOL transmittance of UV-B radiation is equivalent to that of a 15-year-old crystalline lens. Conclusions If optical radiation exposure is responsible for welders' increased risk of uveal melanoma, then UV-B radiation is the most probable causative agent and spectacle wear is a potential confounding factor in epidemiologic studies of ocular melanoma. Welders under 30 years of age are at greater risk for welding maculopathy than older welders. Children, adults under 30 years of age, and pseudophakic individuals with UV-transmitting IOLs should wear sunglasses in bright environments because of the UV-B window in their crystalline lenses or IOLs.

Aim: To analyse how age-related losses in crystalline lens transmittance and pupillary area affect circadian photoreception and compare the circadian performance of phakic and pseudophakic individuals of the same age. Methods: The spectral sensitivity of circadian photoreception peaks in the blue part of the spectrum at approximately 460 nm. Photosensitive retinal ganglion cells send unconscious information about environmental illumination to non-visual brain centres including the human body’s master biological clock in the suprachiasmatic nuclei. This information permits human physiology to be optimised and aligned with geophysical day–night cycles using neural and hormonal messengers including melatonin. Age-related transmittance spectra of crystalline lenses and photopic pupil diameter are used with the spectral sensitivity of melatonin suppression and the transmittance spectra of intraocular lenses (IOLs) to analyse how ageing and IOL chromophores affect circadian photoreception. Results: Ageing increases crystalline lens light absorption and decreases pupil area resulting in progressive loss of circadian photoreception. A 10-year-old child has circadian photoreception 10-fold greater than a 95-year-old phakic adult. A 45-year-old adult retains only half the circadian photoreception of early youth. Pseudophakia improves circadian photoreception at all ages, particularly with UV-only blocking IOLs which transmit blue wavelengths optimal for non-visual photoreception. Conclusions: Non-visual retinal ganglion photoreceptor responses to bright, properly timed light exposures help assure effective circadian photoentrainment and optimal diurnal physiological processes. Circadian photoreception can persist in visually blind individuals if retinal ganglion cell photoreceptors and their suprachiasmatic connections are intact. Retinal illumination decreases with ageing due to pupillary miosis and reduced crystalline lens light transmission especially of short wavelengths. Inadequate environmental light and/or ganglion photoreception can cause circadian disruption, increasing the risk of insomnia, depression, numerous systemic disorders and possibly early mortality. Artificial lighting is dimmer and less blue-weighted than natural daylight, contributing to age-related losses in unconscious circadian photoreception. Optimal intraocular lens design should consider the spectral requirements of both conscious and unconscious retinal photoreception.

Driving requires effective coordination of visual, motor, and cognitive skills. Visual skills are pushed to their limit at night by decreased illumination and by disabling glare from oncoming headlights. High intensity discharge (HID) headlamps project light farther down roads, improving their owner's driving safety by increasing the time available for reaction to potential problems. Glare is proportional to headlamp brightness, however, so increasing headlamp brightness also increases potential glare for oncoming drivers, particularly on curving two lane roads. This problem is worse for older drivers because of their increased intraocular light scattering, glare sensitivity, and photostress recovery time. An analysis of automobile headlights, intraocular stray light, glare, and night driving shows that brightness rather than blueness is the primary reason for the visual problems that HID headlights can cause for older drivers who confront them. The increased light projected by HID headlights is potentially valuable, but serious questions remain regarding how and where it should be projected.

PURPOSE: To describe the optical coherence tomography (OCT) findings in two patients with welder's maculopathy. METHODS: Retrospective cases series. In addition to examination by slit lamp biomicroscopy, color fundus photographs and OCT images were obtained from patients with welder's maculopathy. RESULTS: Both patients had a history of bilateral decreased central vision after welding without appropriate eye protection. Yellowish foveal spots developed in the acute stage, evolving over several months into well demarcated lamellar foveal defects with surrounding retinal pigment epithelium changes. OCT showed interruption of the inner high reflective layer (HRL) corresponding to the level of the outer neurosensory retina. These appearances are similar to those seen in solar maculopathy. CONCLUSIONS: OCT shows disruption of the inner HRL in late welder's maculopathy. These appearances are similar to those seen in late solar maculopathy. OCT can be a useful tool in confirming the diagnosis and understanding the pathogenesis of photic maculopathy.

Ophthalmoscopic contact lenses for transpupillary thermotherapy (TTT) must provide effective visualization of retinal treatment sites and transmission of infrared diode laser radiation. Selection and proper use of retinal laser lenses requires knowledge of their lateral magnification, laser beam magnification factor, field of view and resolution. Optical performance is analyzed for Goldmann-type lenses and a series of inverted image lenses of differing magnification. Goldmann lenses have the highest resolution, but inverted image lenses of comparable magnification have 2.5 times or more their field of view. Inverted image lenses of similar magnification can differ in resolution. They require 2-4% more incident laser power to produce the same retinal irradiance as a Goldmann lens, but this difference is small in comparison to other clinical variables. Tilting an ophthalmoscopic contact lens up to 15 degrees causes little distortion in the circularity of the retinal spot formed by a laser beam or difference in retinal irradiance across the spot. Inverted image lenses produce higher anterior segment irradiances than Goldmann-type lenses, but anterior segment injuries are less likely in TTT than conventional visible light, short-pulse retinal photocoagulation because of the comparatively low irradiances used in TTT and the decreased absorption of diode laser infrared radiation in ocular media and melanin.

Purpose. To evaluate the efficacy of transpupillary thermotherapy (TTT) for the treatment of occult choroidal neovascularization. Methods. A retrospective, noncomparative case series of 57 eyes of 52 patients who presented with occult subfoveal CNV and were treated with TTT. Results. 83% of eyes were either stable (+/− one line) or showed improvement in visual acuity. 83% of eyes showed stabilization of their exudative process after one TTT treatment as evidenced by resorption of subretinal and/or intraretinal exudate or hemorrhage. Nine percent of eyes developed classic CNV during the mean follow-up time of ten months. Conclusions. TTT appears to stabilize the exudative process in eyes with occult CNV. A prospective, sham-controlled, randomized study (TTT4CNV Clinical Trial) is currently underway to directly compare TTT to the natural history of occult CNV

* OBJECTIVE: To provide a biophysical foundation for using transpupillary thermotherapy (TTT) to manage choroidal neovascularization in age-related macular degeneration (ARMD). * METHODS: Retinal temperature rise in laser therapy is proportional to retinal irradiance (laser power/area) for a particular spot size, exposure duration, and wavelength. TTT is a low irradiance, large spot size, prolonged exposure (long-pulse), infrared laser photocoagulation protocol. Results from an experimentally confirmed, finite element model of retinal light absorption and heat conduction are used to analyze laser parameter selection and its consequences. Results from apoptosis, heat shock protein and hyperthermia research are used to examine how chorioretinal damage from clinical procedures might be reduced. * RESULTS: Chorioretinal thermal equilibration occurs during long-pulse TTT photocoagulation. Retinal temperature increases are similar in the RPE where laser radiation absorption is significant and in the adjacent neural retina where there is negligible radiation absorption. For parameters used to treat occult choroidal neovascularization in lightly-pigmented fundi (800-mW, 810-nm, 3-mm retinal spot diameter, 60-sec exposure duration), the maximum chorioretinal temperature elevation is calculated to be roughly 10°C, significantly lower than the 20°C temperature elevations measured in threshold, conventional short-pulse retinal photocoagulation. * CONCLUSIONS: To achieve a preselected temperature rise, TTT laser power must be increased or decreased in proportion to the diameter rather than the area of the laser spot. Clinical power settings should be adjusted for fundus pigmentation and media clarity because both of these factors affect absorbed retinal irradiance and thus retinal temperature rise. Noninvasive thermal dosimetry currently is unavailable for clinical retinal photocoagulation, but potential thermometric techniques include MRI, liposomal-encapsulated dyes, multispectral imaging or reflectometry, and subretinal or episcleral thermometry. TTT may be useful not only as independent therapy, but also as an adjunct to PDT, antiangiogenic drugs and ionizing radiation therapy in the management of neovascular ARMD. Low temperature, longpulse photocoagulation is a potential strategy for decreasing neural retinal damage in subsequent TTT or short-pulse photocoagulation and perhaps even for treating glaucoma or retinal degenerations. [Ophthalmic Surg Lasers 2000;31:359-373]

Retinal injuries from industrial or military lasers are uncommon, but laser accidents can injure the retina and destroy central vision, permanently. Key principles of retinal anatomy and psychophysics provide a basis for understanding laser-retinal interactions, retinal trauma, and treatment options. Immediate vision loss after a laser accident depends primarily on the location and extent of retinal damage and vitreoretinal hemorrhage. Prompt ophthalmic evaluation of accident victims is indicated to determine the nature and severity of injuries to the cornea, iris, crystalline lens, and retina. There are no clinically proven therapies for minimizing the acute effects of retinal laser injuries, but vitreoretinal surgery is useful for managing complications such as persistent vitreous hemorrhages, macular holes, and epiretinal membranes. The best way to manage laser trauma is to prevent it.

* BACKGROUND AND OBJECTIVES: Plasma and cavitation bubble formation during optical breakdown in aqueous media may produce hydroxyl (*OH) radicals. The authors' objectives were to detect *OH produced by a neodymium:yttriumaluminum-garnet (Nd:YAG) laser photodisruptor and to determine *OH concentration in relation to laser energy. * MATERIALS AND METHODS: *OH was assayed by measuring absorbance of triiodide (I 3 ^sup -^) in a potassium iodide (KI) solution exposed to optical breakdown by an Nd:YAG laser. The concentration-dependent reduction of radical production in relation to cystamine concentration was evaluated. * RESULTS: I 3 ^sup -^ concentration increased linearly with total irradiation energy and decreased exponentially with increasing cystamine concentration. *OH concentration was calculated using extinction coefficients of I 3 ^sup -^ and chemical equations relating I 3 ^sup -^ formation to *OH. * CONCLUSIONS: The authors calculated that -4X1 0^sup -12^ moles of *OH are produced in a typical posterior capsulotomy of 100 mJ of total energy. This *OH concentration could produce strand breaks in -0.4% of vitreous hyaluronic acid molecules, but is unlikely to produce clinical effects. [Ophthalmic Surg Lasers 1997;28:582-589.]

We developed a clinical strategy for dealing with situations in which ophthalmoscopic examination and vitreoretinal surgery are difficult in patients with an ARRAY® refractive multifocal intraocular lens (IOL) implant. The ARRAY zonal-progressive IOL has a central 2. 1 -mm distance-vision zone for optically-unobstructed posterior pole observation. A concentric near-vision zone (+3.5-diopter add) surrounds this central zone. Optical ray-tracing is used to determine how a 2.1-mm pupil limitation restricts monocular and binocular retinal image size in head-mounted, slitlamp, and operating microscope ophthalmoscopy. A 2.1-mm pupil decreases the retinal field of view of high magnification, narrow field lenses much more than that of wider-field, lower magnification lenses. This "worst-case" analysis suggests an ophthalmoscopic strategy, but is not strictly valid for the ARRAY lens because the near-vision zone surrounding its 2.1-mm central zone is not opaque. The near-vision zone contributes defocused information to the ophthalmoscopic image, diminishing its resolution and depth information. Wide-field, low magnification lenses are potentially less problematic than higher magnification lenses for examining and treating patients with an ARRAY IOL implant. This strategy is useful for panretinal photocoagulation or photodynamic therapy, but not for procedures requiring high magnification stereoscopic vision such as macular vitreoretinal surgery. [Opthalmic Surg Lasers 2002;33:74-76]

A 67-year-old woman had decreased visual acuity in her left eye and disturbing concentric ring dysphotopsias after bilateral implantation of ReSTOR (SN60D3; Alcon Laboratories, Inc., Fort Worth, TX) diffractive multifocal intraocular lenses (IOLs). Monochromatic (820-nm infrared and 488-nm red-free) scanning laser ophthalmoscopy (SLO) documented central retinal concentric ring patterns resembling the patient’s drawings of her dysphotopsia, prompting investigation of the relationship of these phenomena. Similar SLO findings were present in four eyes of three additional ReSTOR pseudophakes without dysphotopsia, but absent in monofocal pseudophakes or phakic individuals. Optical analysis shows that concentric ring SLO imaging artifacts can be caused by coherent reflection of monochromatic laser radiation off the diffractive optical element on the IOL’s anterior surface, whereas concentric ring dysphotopsias are due to diffraction or projection of broad spectrum light sources in ordinary environments. Thus, the IOL’s diffractive optics is the origin of both concentric ring dysphotopsia and SLO artifacts, but diffraction or projection causes the visual phenomenon, whereas coherent reflection produces the imaging anomaly.

A three-dimensional model of corneal thermal response to CO(2) laser radiation is constructed and numerical solutions for temperature rise are computed. Power distribution in the laser beam and a conducting air-cornea interface are considered explicitly. It is found that the radial distribution of temperature increases produced by a gaussian beam is also gaussian, for brief exposures. The corneal damage threshold is examined in terms of this result.

Environmental illumination profoundly influences human health and well-being. Recently discovered photoreceptive retinal ganglion cells (pRGCs) are primary mediators of numerous circadian, neuroendocrine and neurobehavioral responses. pRGCs provide lighting information to diverse nonvisual (non-image-forming) brain centers including the suprachiasmatic nuclei (SCN) which serve as the body's master biological clock. The SCN exert functional control over circadian aspects of physiology. The timing and strength (amplitude) of SCN rhythmic signals are affected by light exposure. Light deficiency may attenuate SCN function and its control of physiological and hormonal rhythms which in turn can result in a cascade of adverse events. Inadequate pRGC photoreception cannot be perceived consciously, but may aggravate many common age-associated problems including insomnia, depression and impaired cognition. In this review we (1) summarize circadian physiology, emphasizing light's critical role as the most important geophysical timing cue in humans; (2) analyze evidence that typical residential lighting is insufficient for optimal pRGC requirements in youth and even more so with advancing age; (3) show how ocular aging and cataract surgery impact circadian photoreception; and (4) review some of the diverse morbidities associated with chronodisruption in general and those which may be caused by light deficiency in particular.

A young Caucasian child presented 2 years after diminished visual acuity was first recorded by a primary care physician. The patient had passed school vision tests previously. The patient was unaware of nyctalopia, hemeralopia or diminished colour vision. Since seeking ophthalmic attention, the visual acuity in each eye had fluctuated between 20/50 and 20/150. The patient had first seen a retinal specialist 14 months prior to presentation, and bilateral circumscribed foci of subfoveal retinal pigment epithelium (RPE) altered pigmentation had been noted. Mild bilateral disc elevation, of unknown significance, had also been noted. An ERG had been reported as essentially normal, and an EOG had shown Arden ratios above 2.4 in both eyes. The patient's mother recalled that approximately 2 years before presentation to us, she noticed at least once that the patient had a prolonged period of mydriasis. She took her child to the local emergency room where she was told that the mydriasis was related to methylphenidate use. There was no relevant family history. The patient had been treated with methylphenidate for attention deficit hyperactivity disorder for 6 years. One year before presentation, an additional diagnosis of oppositional defiance disorder was made. At this stage, the medications were changed to dexmethylphenidate and aripiprazole. Best corrected visual acuity was 20/80 in the right eye and 20/63 in the left. …

Three patients suffered photic or thermal laser injuries at unintended sites because of reflection from gas-fluid interfaces in eyes containing gas. Fresnel's equations predict the amount of light transmitted or reflected at optical interfaces. Application of Fresnel's equations demonstrate that significant laser reflection occurs at gas-fluid or fluid-gas interfaces, especially at high angles of incidence. Photocoagulation across gas-fluid or fluid-gas interfaces should be avoided to reduce the risk of unintended damage from reflected light. If photocoagulation must be performed across an interface, the surgeon should minimize the angle of incidence of the treatment laser beam, use a divergent beam, and consider the location and intensity of the reflected beam. Because of the higher phototoxicity of blue light, photocoagulation with blue-green lasers across gas-fluid or fluid-gas interfaces is undesirable. Proper polarization of the treatment laser beam may significantly reduce laser reflectance.

The branching patterns of retinal arterial and venous systems have characteristics of a fractal, a geometrical pattern whose parts resemble the whole. Fluorescein angiogram collages were digitised and analysed, demonstrating that retinal arterial and venous patterns have fractal dimensions of 1.63 +/- 0.05 and 1.71 +/- 0.07, respectively, consistent with the 1.68 +/- 0.05 dimension of diffusion limited aggregation. This finding prompts speculation that factors controlling retinal angiogenesis may obey Laplace's equation, with fluctuations in the distribution of embryonic cell-free spaces providing the randomness needed for fractal behaviour and for the uniqueness of each individual's retinal vascular pattern. Since fractal dimensions characterise how completely vascular patterns span the retina, they can provide insight into the relationship between vascular patterns and retinal disease. Fractal geometry offers a more accurate description of ocular anatomy and pathology than classical geometry, and provides a new language for posing questions about the complex geometrical patterns that are seen in ophthalmic practice.

Aim: Monochromatic and chromatic aberrations limit the visual performance of pseudophakic eyes. Chromatic aberration is caused by the chromatic dispersion of optical materials which can be characterised by their Abbe numbers. This study examines how chromatic dispersion affects pseudophakic optical performance at different wavelengths and spatial frequencies. Methods: Abbe numbers were measured for acrylic and silicone intraocular lenses (IOLs). A schematic eye model based on cataract population data was used to compute monochromatic and photopic polychromatic modulation transfer functions (MTFs) for pseudophakic eyes with aspheric IOLs. IOL Abbe numbers were varied without changing other eye model parameters to determine how chromatic dispersion affects pseudophakic MTF and chromatic difference of refraction. Additional calculations were performed for (1) acrylic or silicone materials and (2) high-pass optical filters blocking either UV radiation or UV radiation and short wavelength visible light. Results: Shorter wavelengths account for approximately two thirds of pseudophakic chromatic difference of refraction or longitudinal chromatic aberration. Increasing Abbe number (reducing chromatic dispersion) decreases total chromatic difference of refraction and increases photopic polychromatic MTF. For a specific spatial frequency, there is an effective pseudophakic depth of wavelength over which a particular MTF level is achieved or exceeded. Depth of wavelength narrows with decreasing Abbe number or increasing spatial frequency. Blue-blocking IOL chromophores improve photopic MTF performance by less than 1.5%. Conclusions: Most pseudophakic longitudinal chromatic aberration arises from the chromatic dispersion of IOLs rather than the cornea and other ocular media. Increasing the Abbe number of optic materials improves overall pseudophakic optical performance. Optical transmission of medium and high spatial frequency modulation information has a spectrum similar to photopic luminous efficiency, accounting for the inability of blue-blocking chromophores to improve photopic pseudophakic contrast sensitivity significantly and demonstrating the excellent mutual adaptation of modulation transfer by the eye’s optics and management of that data by the retina and brain.

Aim: To analyse how intraocular lens (IOL) chromophores affect retinal photoprotection and the sensitivity of scotopic vision, melanopsin photoreception, and melatonin suppression. Methods: Transmittance spectra of IOLs, high pass spectral filters, human crystalline lenses, and sunglasses are used with spectral data for acute ultraviolet (UV)-blue photic retinopathy (“blue light hazard” phototoxicity), aphakic scotopic luminous efficiency, melanopsin sensitivity, and melatonin suppression to compute the effect of spectral filters on retinal photoprotection, scotopic sensitivity, and circadian photoentrainment. Results: Retinal photoprotection increases and photoreception decreases as high pass filters progressively attenuate additional short wavelength light. Violet blocking IOLs reduce retinal exposure to UV (200–400 nm) radiation and violet (400–440 nm) light. Blue blocking IOLs attenuate blue (440–500 nm) and shorter wavelength optical radiation. Blue blocking IOLs theoretically provide better photoprotection but worse photoreception than conventional UV only blocking IOLs. Violet blocking IOLs offer similar UV-blue photoprotection but better scotopic and melanopsin photoreception than blue blocking IOLs. Sunglasses provide roughly 50% more UV-blue photoprotection than either violet or blue blocking IOLs. Conclusions: Action spectra for most retinal photosensitisers increase or peak in the violet part of the spectrum. Melanopsin, melatonin suppression, and rhodopsin sensitivities are all maximal in the blue part of the spectrum. Scotopic sensitivity and circadian photoentrainment decline with ageing. UV blocking IOLs provide older adults with the best possible rhodopsin and melanopsin sensitivity. Blue and violet blocking IOLs provide less photoprotection than middle aged crystalline lenses, which do not prevent age related macular degeneration (AMD). Thus, pseudophakes should wear sunglasses in bright environments if the unproved phototoxicity-AMD hypothesis is valid.

Background/aim: Subvisible micropulse diode laser photocoagulation localises retinal laser damage because brief micropulses allow little time for heat conduction to spread temperature rise from the retinal pigment epithelium to the neural retina. Treatment power is often chosen as a multiple of that needed for visible continuous wave lesions. The authors measured clinical laser powers needed for visible end point micropulse and continuous wave diode laser retinal photocoagulation. Methods: Six parallel rows of 10 diode laser (810 nm) burns were made in the superior peripheral retina of six consecutive patients undergoing their initial frequency doubled Nd:YAG (532 nm) panretinal photocoagulation for proliferative or severe non-proliferative diabetic retinopathy. All photocoagulation exposures were 125 µm in retinal diameter and 0.2 seconds in duration. Micropulse exposures were performed with 500 Hz, 0.3 ms micropulses. The minimal power needed (1) for visible continuous wave diode photocoagulation was determined from two adjacent rows of laser lesions and (2) for visible micropulse diode photocoagulation from four additional adjacent rows of laser lesions. Fluorescein angiograms and red-free fundus photographs were obtained immediately and 6 days after laser photocoagulation in each patient. Calculations were performed to determine the extent to which clinical parameters exceeded ANSI Z136.1-2000 maximal permissible exposure (MPE) levels for laser exposure. Results: Continuous wave and micropulse lesions typically required 300 mW (60 mJ) and 1800 mW (54 mJ), respectively. Visible continuous wave and micropulse lesions exceeded MPE levels by multiples of 36× and 133×, respectively. Laser energies were similar for visible continuous wave and micropulse lesions. Conclusion: Visible micropulse lesions require 6× more power but roughly the same energy as visible continuous wave lesions. No significant difference was demonstrable in the minimal power needed for photographically and angiographically apparent diode micropulse lesions. MPE levels are designed to provide a 10× safety margin. This safety margin was 3.7× greater for micropulse than continuous wave diode laser photocoagulation.

A variety of optical and electro-optical instruments are used for both diagnostic and therapeutic applications to the human eye. These generally expose ocular structures to either coherent or incoherent optical radiation (ultraviolet, visible, or infrared radiation) under unique conditions. We convert both laser and incoherent exposure guidelines derived for normal exposure conditions to the application of ophthalmic sources.

Aim: To report the visual and clinical outcomes of a pilot study of subthreshold diode micropulse (SDM) laser photocoagulation for clinically significant diabetic macular oedema (CSMO). Methods: The results of infrared (810 nm) SDM laser photocoagulation for CSMO were retrospectively reviewed in 95 eyes of 69 consecutive patients with mild to moderate non-proliferative diabetic retinopathy. The same laser parameters were used for each patient. Only the number of laser applications varied between patients, depending on their macular findings. Primary outcome measures were Snellen visual acuity, fluorescein angiographic leakage, and CSMO status. Results: Visual acuity was stable or improved in 85% of treated eyes, with a mean follow up of 12.2 months (range 3–29 months). CSMO decreased in 96% and resolved in 79% of treated eyes. No adverse laser events occurred. No laser lesions were detectable ophthalmoscopically or angiographically after treatment, consistent with calculations based on ANSI Z136.1 laser safety standards suggestive of only histologically detectable tissue effects at the laser exposure levels. No laser scarring was observed during the follow up period. Conclusion: Subthreshold diode micropulse laser photocoagulation minimises chorioretinal damage in the management of CSMO and demonstrates a beneficial effect on visual acuity and CSMO resolution. Prospective studies are needed to fully evaluate this technique.

Transpupillary thermotherapy (TTT) is a subthreshold, low irradiance, long exposure duration, large spot size, infrared diode laser protocol. Retinal temperature increases in TTT for choroidal neovascularization (CNV) are substantially lower than those in conventional short-pulse photocoagulation, but they are maintained for 60 seconds to achieve therapeutic results. Treatment power is adjusted for retinal lesion size, chorioretinal pigmentation, macular elevation and media clarity. TTT uses 810-nm diode laser infrared radiation, which has no significant retinal phototoxicity. A parfocal laser delivery system is required to assure uniformity of irradiance across large diameter treatment spots. Relative contraindications for TTT include dense subretinal hemorrhage, prior focal photocoagulation and serous RPE detachment. Adverse events are rare, and include decreased vision and retinal arteriole occlusion. Randomized, prospective multi-center trials are underway to compare the results of TTT for occult CNV in age-related macular degeneration to the natural history of the disorder. Imaging, electrophysiologic or thermometric techniques may ultimately provide intra-operative or post-operative monitoring to assure the adequacy of TTT for CNV, despite the absence of ophthalmoscopically visible lesions.

(2001). Transpupillary thermotherapy – introduction. Seminars in Ophthalmology: Vol. 16, No. 2, pp. 53-54.