ABSTRACT
All methods of laser radiation therapy currently used in clinical practice are positioned as safe in terms of possible negative effects on the eye and surrounding tissues. PURPOSE: To assess possible changes in the macular region of the retina and thickness of the peripapillary retinal nerve fiber layer (RNFL) according to the results of a dynamic study of OCT parameters after laser operations in the iris-lens diaphragm area. MATERIAL AND METHODS: Optical coherence tomography (OCT) was performed on 34 pseudophakic patients (43 eyes) with clinical signs of secondary cataract with best corrected visual acuity (BCVA) of at least 0.3, and on 28 patients (38 eyes) with relative papillary block before laser intervention and 1 hour, 1 day, 3 days, 7 days, 1 and 6 months after surgery. The changes in the thickness of the retina in 9 standard ETDRS areas, and the thickness of the ganglion cells layer and peripapillary RNFL were analyzed. RESULTS: In both groups of patients during the entire observation period, there was no fundamental change in the thickness of the peripapillary RNFL and the ganglion cell complex (all p>0.05). According to OCT, retinal thickness in both groups significantly increased an hour after laser irradiation in 5 out of 9 ETDRS areas. The retinal thickness returned to preoperative values in the group of patients with Nd:YAG laser posterior capsulotomy on the 3rd day after surgery, and after 1 week in the group with Nd:YAG laser iridectomy. Retinal thickness in the macular area did not change significantly during the follow-up. CONCLUSION: Laser operations in the iris-lens diaphragm area have a negligible effect on the thickness of the retina, as measured by the OCT method, do not affect the thickness of the ganglion cells layer or peripapillary RNFL, and is safe for the central zone of the retina.
Subject(s)
Diaphragm , Lens, Crystalline , Humans , Iris/diagnostic imaging , Iris/surgery , Nerve Fibers , Retinal Ganglion CellsABSTRACT
The present review covers the use of chorioretinal photocoagulation, which is now a popular treatment for many diseases of the ocular fundus. The review includes a detailed 50-year history of the technology with account to both Russian and foreign achievements. The current state of the field is shown through Russian and foreign literature data. A particular emphasis is placed on subthreshold, pattern, and navigated techniques. Breakthrough solutions, such as optoacoustic monitoring, that ensure high precision of the procedure, maximum saving of tissues, and high therapeutic effectiveness are described.
Subject(s)
Eye Diseases/therapy , Laser Therapy/methods , Eye Diseases/diagnosis , Fundus Oculi , Humans , Ophthalmoscopy/methods , Pupil , RussiaABSTRACT
The effect of laser treatment on ocular fundus tissues depends on quite a number of factors, mostly uncontrollable, hence, laser output parameters may vary dramatically even within the same fundus. In classical procedure ('threshold' laser coagulation), these parameters are adjusted to ophthalmoscopically visible tissue color changes at the site of coagulation. However, this method does not work with modern subthreshold techniques, that are more tissue-saving and thus, produce no immediate and visible changes in the retina. Calculation methods that are used instead are much less accurate. Photoacoustic monitoring may become a real breakthrough in this field. The method involves acoustic analysis of the response to soft and short laser pulses ('test' pulses). Heating of the target by the main therapeutic laser causes alterations in its physical properties and, consequently, the laser-induced acoustic signal. This gives us an ability to monitor the temperature and thus, to evaluate the clinical effect of coagulation despite the absence of visible changes at the site. The most promising techniques of photoacoustic monitoring that are being developed are discussed here.
