[Comparative evaluation of transscleral laser exposure in anatomical experiment]. / Sravnitel'naya otsenka lazernogo transskleral'nogo vozdeistviya v usloviyakh anatomicheskogo eksperimenta.

PURPOSE: This study comparatively analyzed the morphology of eye tissues after laser exposure using the latest generation of transscleral laser techniques - micropulse transscleral cyclophotocoagulation (MP-TSCPC) and laser activation of scleral hydropermeability (LASH) - in an anatomical experiment. MATERIAL AND METHODS: The study used pulsed-periodic radiation of an Er-glass fiber laser (λ=1.56 µm) and radiation of a diode laser (λ=0.81 µm) in the micropulse mode. A comparative morphological evaluation of histological preparations of target scleral and ciliary body (CB) tissues was performed with the study of laser-induced changes occurring after LASH and MP-TSCPC. RESULTS: The study of histological preparations obtained after MP-TSCPC and LASH did not reveal any noticeable signs of an inflammatory reaction or significant destructive changes. There were no signs of pronounced coagulative changes in the form of disorganization of connective and muscle tissue in the exposure area. At the same time, MP-TSCPC was accompanied by thinning and discontinuity of the CB pigment epithelium in the projection of its flat part and expansion of the gaps between the anterior connective tissue fibers fixing the CB to the sclera, which is likely a factor contributing to uveoscleral outflow. After LASH, in the irradiated areas at the level of the outer layers of the sclera (¾ of its thickness) located in the projection of the flat part of the ciliary body, multiple slit-like cavities and enlargements (stretching) of interfiber spaces were revealed with simultaneous compaction of the inner part of the sclera (» of its thickness). CONCLUSION: The identified morphological changes may indicate certain differences in the mechanisms of intraocular pressure (IOP) reduction after MP-TSCPC and LASH. The results of this study suggest that the enhancement of uveoscleral outflow of intraocular fluid and the hypotensive effect after MP-TSCPC may be associated with laser-induced expansion of the interspaces between the anterior connective tissue fibers of the CB in the suprachoroidal space. With LASH, the possible mechanism of lowering IOP may be related rather to an increase in transscleral filtration due to the appearance of slit-like interfiber spaces in the sclera, caused by local contraction of scleral fibers in the area of laser exposure. The absence of pronounced destructive changes at the histological level indicates the gentle nature of both laser techniques and the possibility of expanding the indications for the use of LASH in the treatment of glaucoma, including at its earlier stages.

[The first experience of using femtosecond laser in the treatment of anterior capsular contraction syndrome]. / Pervyi opyt primeneniya femtosekundnogo lazera dlya lecheniya perednekapsulyarnogo kontraktsionnogo sindroma.

Prevention and treatment of anterior capsular contraction syndrome (ACCS) is a relevant problem in cataract surgery. PURPOSE: The study was performed to develop a femtosecond laser-assisted technique for anterior capsulotomy in anterior capsular contraction syndrome and assess its preliminary results in preventing the progression of pathological changes in the capsular bag. MATERIAL AND METHODS: The examination and femtosecond laser-assisted treatment without additional surgical intervention was performed in 6 patients (6 eyes) aged 69 to 73 years with anterior capsular contraction syndrome. Femtosecond laser-assisted anterior capsulotomy was performed using the VICTUS system (Technolas Perfect Vision, Germany). Capsulotomy diameter was 4.0-4.5 mm, laser radiation energy - 9000 nJ, laser exposure depth 900-1000 µm. RESULTS: The diameter of the anterior capsulotomy before treatment was 2.85 mm [2.75; 2.93]. After 1 month, the diameter of the anterior capsular opening was 2.88 mm [2.78; 2.96] (p>0.05). One year after femtosecond laser intervention, the anterior capsulotomy opening was almost the same shape and diameter - 2.84 mm [2.74; 2.94] (p>0.05). CONCLUSION: Femtosecond laser-assisted circular capsulotomy is an effective and safe method for preventing the progression of anterior capsular contraction syndrome in the absence of severe IOL decentration and for maintaining the diameter of the anterior capsular opening of at least 2.5-3.0 mm.

[Morphological evaluation of the results of laser activation of scleral hydropermeability in the treatment of glaucoma]. / Morfologicheskaya otsenka rezul'tatov operatsii lazernoi aktivatsii gidropronitsaemosti sklery v lechenii glaukomy.

PURPOSE: The study attempted to experimentally substantiate the possibility of using the laser activation of scleral hydropermeability (LASH) technique in glaucoma treatment by morphological evaluation of treatment outcomes. MATERIAL AND METHODS: The pulsed-periodic radiation from an Er-glass fiber laser (λ=1.56 µm) was used. The model experiment consisted of evaluating ultrafiltration of fluid through the tissues of human sclera autopsy specimen according to the original technique using neodymium chloride-based labeling agent and scanning electron microscopy. The clinical part of the study consisted of optical coherence tomography (OCT) and laser confocal microscopy of the sclera and conjunctiva (CMSC) performed in vivo immediately after laser treatment in the laser application sites in 5 patients (5 eyes) aged 57 to 68 years with uncompensated advanced (IIIb-c) stage of glaucoma who had previously underwent LASH surgery. RESULTS: Results of morphological evaluation after LASH revealed structural changes indicating increased transscleral ultrafiltration: increased intrastromal hyporeflective areas in the sclera, thinning of collagen fibers, formation of porous structures. Using an original technique involving neodymium chloride-based labeling agent and scanning electron microscopy, we were able to prove the enhancement of transscleral ultrafiltration. The results of the experiment were confirmed by in vivo OCT images of the sclera and CMSC performed in 5 patients with advanced glaucoma after LASH surgery, in which tissue decompaction in the laser-exposed areas was clearly visualized. CONCLUSION: The revealed structural changes indicate the possibility of reducing intraocular pressure after LASH by the means of forming scleral porous structures and increasing transscleral ultrafiltration. Experimentally selected optimal mode of laser exposure (0.66 W with total exposure time of 6 seconds) during LASH helps avoid gross destructive changes in the eye tissues, making the proposed intervention a sparing approach to the treatment of glaucoma.

[Current possibilities of laser surgery on anterior eye segment]. / Sovremennye vozmozhnosti lazernogo vozdeistviya na struktury perednego segmenta glaza.

The article summarizes the experience of recent years in the development and implementation of novel original laser technologies used in surgery of the anterior segment of the eye. The presented technology of laser activation of scleral hydropermeability (LASH) in glaucoma is based on the effect of enhanced transscleral filtration and has been shown as effective and safe, which was confirmed by the results of a comprehensive clinical and experimental study. Development of another technique was associated with the need to improve the safety of laser interventions in anterior capsule contraction syndrome in pseudophakia, and resulted in a proposition to change the configuration of the anterior lens capsule incision from the usual linear-radial to T-shaped laser anterior capsulorhexis. The proposed technology of laser photomydriasis based on near-infrared radiation of the diode laser (0.810 µm) has shown its effectiveness and gentle nature (absence of atrophy of the iris stroma and post-burn pigmentation) in ectopias and pupil deformity.

[Modern approaches to the treatment of anterior capsule contraction syndrome]. / Sovremennye podkhody k lecheniyu perednekapsulyarnogo kontraktsionnogo sindroma.

Anterior capsule contraction syndrome is a specific complication of continuous circular capsulorhexis in various phacoemulsification techniques. Surgical, laser and combined methods have been proposed for its treatment. All approaches in the treatment of anterior capsule contraction syndrome have some advantages, as well as certain problems and difficulties. This review presents the current state of this problem of cataract surgery and possible prospects for improving the treatment.

[Clinical outcomes of laser activation of hydraulic permeability of the sclera in the treatment of advanced glaucoma]. / Klinicheskie rezul'taty lazernoi aktivatsii gidropronitsaemosti sklery v lechenii patsientov s dalekozashedshei stadiei glaukomy.

PURPOSE: This study evaluates the hypotensive effect and the outcomes of intravital morphological changes in the intervention site after laser activation of scleral hydro-permeability (LASH) by pulsed-periodic radiation from an Er-glass fiber laser (λ=1.56 µm) in patients with advanced glaucoma. MATERIAL AND METHODS: LASH surgery was performed in 19 patients (19 eyes) aged 48 to 73 years with uncompensated advanced stage (IIIb-c) glaucoma. In addition to standard methods of investigation, all patients were examined with optical coherence tomography (OCT) and laser confocal microscopy of sclera and conjunctiva (CMSC) at the laser treatment sites, and electronic tonography. RESULTS: The hypotensive effect after LASH in patients with advanced glaucoma was observed in 94.7% (n=18) of cases. The decrease in intraocular pressure (IOP) averaged 24.4% from baseline one month after intervention and 32.96% after six months of follow-up. In 15.7% (n=3) of cases, the recorded IOP decrease was insufficient as its target values were not achieved. However, in the vast majority of patients (n=16), the recorded IOP decrease corresponded to the target values and indicated compensation of the process. Results of complex morphological evaluation after LASH revealed structural changes indirectly indicating possible laser-induced influence on the processes of increased transscleral filtration and uveoscleral outflow. A high positive correlation dependence (r=0.848) was also revealed between the degree of IOP lowering and the increase in the coefficient of ease of aqueous humor outflow, attesting to the fact that IOP lowering was mainly due to the improvement of intraocular fluid outflow. CONCLUSION: The demonstrated efficacy of LASH technology indicates the possibility of its successful application as an independent method of IOP reduction in patients with advanced glaucoma.

[Laser-induced damage to the cornea after YAG laser surgery of anterior segment structures]. / Lazerindutsirovannye povrezhdeniya rogovitsy posle YAG-lazernykh vmeshatel'stv na strukturakh perednego segmenta glaza.

Laser photodestruction (LPD) of tissues is the basis of modern laser reconstructive surgery in ophthalmology. The most common laser technologies based on LPD mechanisms include YAG laser capsulotomy (discission) (LD) of secondary cataract and YAG laser iridectomy (LIE) for glaucoma. Laser reconstructive interventions for secondary cataract, as well as LIE, have a number of advantages over traditional surgery, but at the same time are associated with the risk of complications, including in the cornea. Corneal endothelium is the most susceptible to laser damage, while Descemet's membrane and corneal stroma are injured less often. This review describes cases of iatrogenic perforation and purulent inflammation of the cornea. In the long-term, laser interventions can lead to bullous keratopathy and corneal graft rejection. At this time, the most popular and available among the methods for assessing the cornea after YAG laser interventions is the method of specular microscopy. Ultrasound biomicroscopy is used less commonly. The modern method of corneal confocal microscopy is practically not used for this purpose, and taking into account the risks of developing laser-induced injuries, it indicates its relevance and the need for further research.

[On studying the mechanisms and assessing the safety of Nd:YAG laser irradiation of the posterior lens capsule (experimental and clinical study)]. / K voprosu ob izuchenii mekhanizmov i otsenke bezopasnosti Nd:YAG-lazernoi destruktsii zadnei kapsuly khrustalika (eksperimental'no-klinicheskoe issledovanie).

YAG laser interventions are associated with the risk of complications, including corneal. PURPOSE: To study the mechanisms of laser destruction in exposing the posterior lens capsule (PLC) tissue to Nd:YAG laser irradiation, and to evaluate its side effects on the cornea. MATERIAL AND METHODS: The experiment involved 6 autopsy samples of human posterior lens capsule with different optical and mechanical properties, which were exposed to laser irradiation. We used the Nd:YAG ophthalmic laser LPULSA SYL-9000 Premio manufactured by «LightMed¼ (Taiwan/USA) and an experimental Nd:YAG laser system (1.064 µm). The following parameters were compared: the power of the incident radiation and radiation transmitted through the PLC, the mechanical stresses in the PLC tissue, the kinetic energy of the laser ablation products, and the pressure of gas bubbles during laser exposure in capsule samples of different densities. In the clinical part of the work, the negative effects of Nd:YAG laser on the cornea at different PLC densities were assessed using the endothelial microscope SP 3000P («Topcon¼, Japan). RESULTS: The experiment showed that in hard samples of PLC there are star-shaped point perforations with a diameter of 50±20 µm with partial rarefaction around the point defects. Damage to soft PLC samples in the form of large complete perforations was up to 200 µm in size. The temperature of laser irradiation necessary to achieve breakdown in soft PLC samples was 90 °C, in hard samples - 120 °C. The results of the experiment indicate that the final outcome - destruction of the PLC tissue - is safer to achieve not by increasing the energy, but by increasing the number of laser pulses. Clinical study results confirm a significant effect of the density of PLC on the values of laser energy and on the state of the cornea after laser intervention. CONCLUSION: The experimental data on the mechanisms of laser destruction of the lens capsule should contribute to the development of new and improvement of already known technologies aimed at reducing the risks associated with laser surgeries.

[Technique for laser activation of scleral hydropermeability in the treatment of patients with refractory forms of glaucoma]. / Tekhnologiya lazernoi aktivatsii gidropronitsaemosti sklery pri refrakternykh formakh glaukomy.

Laser cyclodestructive interventions are considered the method of choice in the treatment of refractory glaucoma. However, the traumatic nature of cyclocoagulation makes it necessary to search for more gentle methods of laser treatment. One of the possible directions is the development of laser transscleral technologies that mainly affect the uveoscleral outflow. This article presents a new technique for laser activation of scleral hydropermeability (LASH) using pulse-periodic erbium glass (Er-glass) fiber-optics laser with wave length of 1.56 µm. The article describes the parameters of laser emission and the technique of LASH, and presents the mechanism of reducing intraocular pressure associated with increased transcleral drainage of intraocular fluid by forming new pores in the sclera. The effectiveness and safety of LASH is supported by a detailed example from clinical practice. This technology has proven itself as a possible alternative to the conventional contact transcleral cyclocoagulation.

[Transscleral laser therapy in the treatment of glaucoma]. / Lazernye transskleral'nye tekhnologii v lechenii glaukomy.

Nowadays glaucoma is one of the leading causes of irreversible blindness worldwide. The main goal in preservation of vision in glaucoma patients is reducing intraocular pressure (IOP), which is considered the main controlled risk factor for progression of glaucomatous optic neuropathy. The article discusses the effectiveness and safety of various transscleral laser technologies in the treatment of glaucoma. Modern transscleral laser technologies that affect the uveoscleral drainage and scleral hydro-permeability are less traumatic and more gentle making them promising in the treatment of patients with early stages of glaucoma, and not only in terminal glaucoma with pain syndrome resistant to conventional treatment ("last resort surgery").

[Persistent hyaloid artery in an adult (a case report)]. / Persistiruyushchaya arteriya steklovidnogo tela u vzroslogo (klinicheskoe nablyudenie).

The article presents a clinical case of a functioning hyaloid artery in a 69-year-old patient. The results of OCT-angiography made it possible to detect the presence of blood flow in the projection of the persistent hyaloid artery (PHA) on the cross-section and en-face images. The vascular bed of PHA spreading along the posterior surface of the lens in the form of separate branches was visualized by slit-lamp biomicroscopy. The uniqueness of this clinical case lies in the low probability of such findings in the elderly. The presence of a developing cataract indicates the need for an individual approach in determining treatment strategies. In our opinion, the consistent use of laser coagulation technologies and laser photodestruction of PHA will minimize the risk of hemophthalmos and tractional retinal detachment during the upcoming cataract surgery.

[Atomic force microscopy in the study of retinal structure]. / Atomno-silovaya mikroskopiya v izuchenii struktury setchatki.

The review addresses the current state of atomic force microscopy (AFM) usage in ophthalmology. Briefly presented here are the history of the development of AFM, principles and modes of operation, its advantages, disadvantages, as well as a comparison with other types of microscopy. The review describes the capabilities of AFM in visualization of various structures of the eye. A significant part of the review is devoted to the study of the retina, which arouses great interest among researchers. In particular, the possibilities of AFM for visualization at the submicron level of various structures in the retina, such as the internal limiting membrane, membrane cells, Müller cells, retinal pigment epithelium in their normal state and in the presence of a pathology (age-related macular degeneration, diabetes mellitus) were reviewed. In addition, several study papers were analyzed, providing a base for the judgement of the mechanical properties of said structures. An AFM study of the visual pigment rhodopsin helped identify its dimeric structure. The stability of the rhodopsin molecule was proved to be determined by the degree of strength of its individual segments connected to each other. The AFM method is a highly accurate method that helps solve many fundamental and practical problems, particularly in ophthalmology.

[SMILE keratorefractive surgery technique]. / Keratorefraktsionnaia tekhnologiia SMILE.

Small incision lenticule extraction (SMILE) keratorefractive surgery technique is a laser surgery alternative to common methods that doesn't require laser ablation of the cornea. Despite its novelty, SMILE technique has already demonstrated positive clinical results comparable to Photorefractive Keratectomy (PRK) and Laser-Assisted in Situ Keratomileusis (LASIK), which led to its widespread application in clinical practice. Compared with other keratorefractive techniques, SMILE has a number of distinct advantage including high biomechanical stability of the cornea, low risk of dry eye syndrome, absence of a corneal flap and associated complications, preservation of corneal epithelium. The article describes the most common SMILE modifications, its weak points and possible complications, as well as methods of additional correction of remaining ametropy.

[Retinal changes after laser interventions on anterior segment of the eyeball]. / Izmeneniia setchatki posle lazernykh vmeshatel'stv na strukturakh perednego otdela glaza.

Laser surgery of the cornea, iris, angle of the anterior chamber and other parts of anterior segment of the eye sees wide application in clinical practice. The adverse effects it can cause in the anterior segment are well known and understood. At the same time, changes the treatment method can cause in the posterior segment of the eye - primarily, in macular area of the cornea, which is of great importance, have not been studied sufficiently. Purpose of the review - to consolidate previously published data on changes in the retina after laser intervention on the anterior segment of the eye.

[New biophotonics methods for improving efficiency and safety of laser modification of the fibrous tunic of the eye]. / Novye metody biofotoniki dlia povysheniia éffektivnosti i bezopasnosti lazernykh tekhnologii modifikatsii fibroznoi obolochki glaza.

The article describes a newly developed and tested diffractive optical element (DOE) that converts non-uniform radiation of the laser output into a homogeneous ring. The Gerchberg-Saxton algorithm is shown to be well suited for achieving annular intensity distribution. Testing this ring transducer on threshold-plasticity cornea demonstrated the reversibility of axisymmetric changes in the cornea. Atomic-Force microscopy of the area of maximum stresses in the corneal periphery showed no significant changes in the structure of the cornea when irradiated in the selected mode. Measurement of Young's modulus of the corneal surface areas after their irradiation also revealed no changes in the elastic properties, while examination of the corneal structure demonstrated the absence of significant structural changes in irradiated samples compared with intact ones.

[Complex morphological assessment of anterior capsule of the lens in patients with capsular contraction syndrome (a clinical case study)]. / Kompleksnaia morfologicheskaia otsenka perednei kapsuly khrustalika pri kapsuliarnom kontraktsionnom sindrome (klinicheskoe nabliudenie).

The anterior capsular contraction syndrome (ACCS) in pseudophakic patients is known to be accompanied by postoperative opacity of anterior lens capsule (ALC) and partial or full closure of anterior capsulotomy opening. PURPOSE: To perform complex morphological assessment of ALC in patients with ACCS. MATERIAL AND METHODS: The study involved complex analysis of ALC that was removed due to ACCS in the pseudophakic eye in the setting of diabetes mellitus and past vitreoretinal surgery. The following examination methods were used: light-optical microscopy of ALC samples in the form of polychrome-colored semifine sections using optical microscope Leica DM-2500 (Germany), scanning microscopy of ALC surface with EVO LS10 (Carl Zeiss, Germany) microscope, analysis of chemical element composition and its variation of the ALC sample with energy-dispersive spectrometer Oxford X-Max50 (Oxford, UK). RESULTS: Light-optical microscopy showed altered state and plication of ALC induced by proliferation from inner surface of the fibrocellular tissue, which gradually thickens (up to 360 µm) towards center and causes reduction of anterior capsulotomy opening. Scanning electron microscopy revealed presence of tissue with uneven micro-relief and a porous three-dimensional structure uncharacteristic for capsule on the surface of ALC. Thickness of the fibrous deposition significantly exceeded the thickness of ALC. Evaluation of elemental composition of the fibrocellular tissue showed elevated concentration of sulfur and phosphorus, which indicates high activity of the regenerative process. In the observed case, the regenerative process was of substitute nature because an attempt to restore the lens was accompanied by formation of connective tissue structurally different from original. CONCLUSION: Complex assessment of an isolated ALC sample allowed revelation of the chain of pathological processes accompanying the development of ACCS.

[Combined YAG-laser capsulotomy in pseudophakic patients with anterior capsular contraction syndrome]. / Tekhnologiia kombinirovannoi lazernoi kapsulotomii pri perednekapsuliarnom kontraktsionnom sindrome v artifakichnykh glazakh.

Progressive metaplastic fibrosis of the anterior capsulorhexis opening is a frequent complication of the postoperative period. There is a widely practiced method of anterior capsular contraction syndrome (ACCS) correction through radial anterior laser capsulotomy. Despite many advantages, it can be complicated by unpredictable anterior capsule tearing and intraocular lens (IOL) dislocation into the vitreous Body, which justifies the search for new technical solutions. AIM: to develop a safe technique of combined laser anterior capsulotomy (LAC) in patients with ACCS. MATERIAL AND METHODS: The study included 19 patients (20 eyes) with ACCS. The suggested LAC technique involved two differently directed YAG-laser cuts that could be regarded as a combination of radial anterior capsulotomy and anterior peripheral linear capsulotomy. With the cuts located perpendicularly to each other, the distal end of each radial cut was connected to the middle of each longitudinal cut. RESULTS: The suggested technique allows an increase in the anterior capsulorhexis diameter up to more than twice the pre-laser size. The difference between the average pre- and post-laser capsulorhexis diameters was statistically significant (р<0.0001). Neither case developed an unpredictable anterior capsule tear. CONCLUSION: The safety of the new technique is ensured by preliminary longitudinal cuts that create a barrier against unpredictable radial tears in the capsular bag during radial capsulotomy.

[Morphological assessment of lens capsule after different techniques of cataract extraction]. / Morfologicheskaya otsenka izmenenii kapsuly khrustalika posle razlichnykh sposobov ekstraktsii katarakty.

AIM: to evaluate morphological changes in the posterior lens capsule (LC) after different techniques of cataract extraction. MATERIAL AND METHODS: Eight pseudophakic human autopsy eyes were divided into two groups by the technique used for cataract extraction. Group 1 included 4 eyes following extracapsular cataract extraction (ECCE) and rigid IOL implantation. Group 2 included 4 eyes after minimally invasive cataract surgery (MICS) that involves the use of ultrasound energy. Semithin LC sections were polychromatically stained, visually examined, and imaged for further analysis. RESULTS: There were certain common features in clinical and morphological appearances of lens capsules from either group, including fibrous metaplasia of epithelial cells and/or pseudoregenerative Elschnig-Adamuk pearls on their inner surfaces, more significant in the ECCE group. MICS group, however, demonstrated many distinct and previously undescribed changes. In particular, post-MICS LCs looked swollen, flabby, and even amorphous, their architectonics were disturbed and fibers separated forming micro slit-like spaces, which could be a result of acoustic cavitation caused by ultrasound exposure. We have named this morphological type of secondary cataract «hyaloid-like¼. CONCLUSION: Clinical and morphological type of postoperative LC opacification as well as its severity depends, to a certain extent, on the technique used for cataract extraction. Hyaloid-like opacifications are typical of minimally invasive surgery involving the use of ultrasound and often show no 'classic' changes (fibroproliferative and pseudoregenerative). The latter is explained by the fact that the posterior LC, which has lost its biomechanical properties, can no longer be a substrate for proliferating cells.

[Chemical microanalysis of mineral deposits on explanted hydrophilic acrylic intraocular lenses].

AIM: to perform chemical microanalysis of mineral deposits on the surface of explanted hydrophilic acrylic intraocular lenses (IOL). MATERIAL AND METHODS: Two soft IOLs made of hydrophilic acryl (one, however, hydrophobic surface coated) and explanted 3 and 6 years after implantation were examined by scanning electron microscopy (EVO LS10, "Karl Zeiss", Germany). Chemical composition of the lens surface was studied using an energy-dispersive spectrometer (EDS X-Max50, Oxford, Great Britain). RESULTS: Chemical microanalysis allowed identification of the deposits, which turned out to be non-stoichiometric hydroxylapatite (also, hydroxyapatite (HA)) crystals with zinc impurity (up to 1.4%weight). CONCLUSION: The two samples represent two stages of a single process. The early stage is associated with newly formed HA crystals that are unable to cause any significant changes to the lens surface. However, as spherocrystals grow, they exert a crystallization effort that moves their growth centers apart with subsequent lens rupture and deformation. Crystal morphology undergoes dynamic changes: while primary (newly formed) crystals are sheaf-like, mature are spheres. A growing HA is non-stoichiometric. Zinc abundance accounts for appearance of its separate mineral phase. Hydrophilic properties of acrylic polymer determine its high affinity for HA crystals. Hydrophobic coating (sample no.1) does not completely prevent lens opacification due to mineral deposits on its surface.

[Analyzing causes for opacification of acrylic IOLs].

AIM: to study the nature of intraocular lens (IOL) opacification depending on the patient's ocular status and general condition. MATERIAL AND METHODS: A total of 9 patients (9 eyes) with 3-6 year history of progressive IOL opacification were enrolled. All the IOLs were acrylic (either hydrophilic--7 cases, or hydrophobic--2 cases). Two patients had their IOLs exchanged due to opacification. Six patients earlier underwent glaucoma surgery. Two patients were type 2 diabetic. Slit lamp biomicroscopy and optical microscopy were used for IOL examination. RESULTS: The surface of hydrophilic acrylic lenses appeared bumpy because of multiple variously shaped translucent granules separated by a chaotic network of furrows and microfractures and located predominantly in the optic zone. In a more severe case, a bowl-shaped impression was observed in the area of opacification. Surface changes of hydrophobic acrylic lenses were in the form of isolated and confluent glistening formations (microcavities). CONCLUSION: Signs of IOL degradation develop over a long period of time (3-6 years, in our experience) and mostly involve the anterior surface of the lens optic. Ocular comorbidity, glaucoma in particular, as well as other surgery and/or therapeutic treatment following IOL implantation may contribute to its opacification. Analysis of published data and own observations suggest that hydrophobic IOLs should be preferred in patients with concomitant diseases, especially diabetes mellitus. Granular deposits, if accumulate, may lead to deformation of the lens optic, as confirmed by the bowl-like impression in one of the explanted hydrophilic IOLs.