Q-switched neodymium: YAG laser surgery of the vitreous

Vision degrading myodesopsia from vitreous floaters in the young: An important aspect of myopia

Vitreous floaters are visual phenomena resulting from floating opacities inside the eye that disturb vision. The opacities consist of microscopic collagen fibers that aggregate in myopia and during aging. These collagen fibers are then seen as irregular, sometimes worm-like shadows or structures of a translucent to black color. Because of the floating aspect, they tend to follow the movements of the eye, causing distress and having a negative impact on a patient's quality of life due to degradation in contrast sensitivity function. This is referred to as vision degrading myodesopsia (VDM). The overall importance of floaters and their effect on quality of life gained attention in recent years. While the existence of floaters alone is labeled as harmless, there is an increasing group of young people suffering from VDM. This coincides with the growing prevalence of myopia. Indeed, myopia and myopic vitreopathy are the major causes of VDM in the young. This aspect of myopia, however, is often overlooked. We review the current research status in floater formation, quality of life impact, symptom assessment, localization and therapeutic options for vitreous floaters from the perspective of a myopic, potentially younger patient group.

Management of vitreous floaters: a review

PURPOSE OF REVIEW

Vitreous floaters, characterized by the perception of spots or shadows in the visual field, commonly result from posterior vitreous detachment and can cause chronic symptoms in affected patients. The diagnosis of posterior vitreous detachment is typically determined clinically and can sometimes be confirmed with optical coherence topography (OCT) [1 ▪▪ ] . The objective of this review is to review management options for symptomatic vitreous floaters.

RECENT FINDINGS

Symptoms of vitreous floaters may be mild or may significantly affect patient quality of life. Observation is the most common management strategy. Procedural management options include pars plana vitrectomy (PPV) and neodymium-doped yttrium aluminium garnet (Nd:YAG) vitreolysis. PPV is considered the most definitive management option for vitreous floaters. PPV, however, carries inherent risks, notably infection, cataract formation, and retinal detachment [2] . Nd:YAG laser vitreolysis is a less invasive alternative with studies demonstrating varied success [1 ▪▪ ,3,4] .

SUMMARY

This review provides insights into the current state of knowledge regarding the management of vitreous floaters and can guide clinical decision-making.

Safety of YAG laser vitreolysis for intraocular tissues: analysis of postoperative complications

PURPOSE

To evaluate the safety of yttrium-aluminum-garnet (YAG) laser vitreolysis for intraocular tissues.

METHODS

Thirty-six New Zealand rabbits were divided as follows: Group 1000 (n = 12) treated with YAG laser of 1000 mJ (5 mJ × 200 shots), Group 2000 (n = 12) treated with YAG laser of 2000 mJ (5 mJ × 400 shots), Group 3000 (n = 12) treated with YAG laser of 3000 mJ (5 mJ × 600 shots). Either a single eye was chosen as the study eye in study groups while the other was untreated as the control group. Intraocular pressure (IOP), slit-lamp, optical coherence tomography (OCT), transmission electron microscopy (TEM), and inflammatory cytokines of aqueous humor (interleukin-1α (IL-1α), interleukin-1β (IL-1β), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α)) were performed to examine the rabbits.

RESULTS

There were no abnormalities in the study groups of IOP, slit-lamp, and OCT examinations. Group 3000 of TEM showed: neutrophils and mitochondrial swelling on day 1, and fibroblasts and neocollagen on day 14. No abnormalities were observed in Group 1000 and 2000 of TEM. Levels of IL-1α and TNF-α increased at 12 h and decreased to baseline on day 3. Levels of IL-1β increased at 12 h and decreased to baseline on day 7. Levels of IL-8 increased on day 1 and decreased to baseline on day 3.

CONCLUSION

YAG laser vitreolysis is safe when the distance is more than 2 mm from ablation point to the lens and the retina, and the total energy is less than 2000 mJ for one treatment procedure.

Evaluation of a new Q-switched Nd:YAG laser on premacular hemorrhage

BACKGROUND

Premacular hemorrhage is among the causes of sudden deterioration of visual acuity. This study aimed to investigate the therapeutic outcomes of a new Q-switched Nd:YAG laser on premacular hemorrhage.

METHODS

Retrospective, case series study of 16 eyes from 16 patients diagnosed with premacular hemorrhage, including 3 cases of Valsalva retinopathy, 8 cases of retinal macroaneurysm, 3 cases of diabetic retinopathy, 1 case of trauma-related hemorrhage and 1 case with leukemia. A 1064nm Q-switched Nd:YAG laser was performed to puncture the posterior hyaloid and inner limiting membrane to drain the hemorrhage.

RESULTS

The success rate of 16 patients with premacular hemorrhage drainage was 100% in this study. Improved visual acuity was observed in each patient.

CONCLUSIONS

In this case series of 16 patients, the new Q-switched Nd:YAG laser was successful in draining premacular hemorrhage with no serious complications.

Retinal Complications after Yttrium-Aluminum-Garnet Laser Vitreolysis for Vitreous Floaters

This is an observational case series of two patients who developed direct retinal damage following neodymium-doped yttrium-aluminum-garnet (YAG) laser treatment for symptomatic vitreous floaters. The first patient developed a vitreous hemorrhage and subsequent branch retinal vein occlusion from laser damage to a major retinal venule. The second patient developed a temporal scotoma from a full-thickness retinal break in the posterior pole requiring laser retinopexy. Direct YAG laser damage to the posterior pole can cause permanent visual deficits. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:610-613.].

Management of vitreous floaters: an international survey the European VitreoRetinal Society Floaters study report

BACKGROUND/OBJECTIVES

To evaluate the efficacy and safety of pars plana vitrectomy for symptomatic floaters.

SUBJECTS/METHODS

Forty-eight vitreoretinal surgeons from 16 countries provided information on 581 eyes who underwent vitrectomy for floaters in this retrospective survey study conducted by European VitreoRetinal Society. Percentage symptomatic improvement, incidence of retinal tears/detachment and post-vitrectomy cataract surgery, and the factors associated with satisfaction and complications were investigated.

RESULTS

Ninety-two percent were satisfied with the results, with 86.3% reporting complete resolution of daily-life symptoms. Overall satisfaction was lower in patients with smaller vitreous opacities at presentation (OR:0.4). Iatrogenic retinal breaks occurred in 29 eyes (5%). Core vitrectomy and cut rates of 1500-4000 or >4000 cuts/min were associated with lower risk of retinal breaks than complete vitrectomy (OR:0.05) and cut rates < 1500 cuts/min (OR: 0.03, 0.12, respectively). Fourteen eyes (2.4%) developed retinal detachment at a median of 3 months; and 84 (48.6%) developed cataract at a median of 16 months post-vitrectomy.

CONCLUSIONS

Pars plana vitrectomy resulted in high patient satisfaction with relatively low rate of severe complications in a large group of patients. The procedure may be safer when core vitrectomy and cut rates > 1500 cuts/min are favoured. Proper patient selection and informed consent are the most important aspects of surgery.

Safety and Efficacy of YAG Laser Vitreolysis for the Treatment of Vitreous Floaters: An Overview

Emerging evidence has suggested that the entoptic phenomena associated with vitreous opacities (i.e. vitreous floaters) are more bothersome than previously believed. In addition, the prevalence of vitreous floaters is likely increasing due to the evolving global pandemic of myopia. The use of YAG laser vitreolysis for the treatment of annoying vitreous floaters has attracted significant attention in recent years as the technique offers a number of potential advantages. Unfortunately, the currently available evidence that is needed to guide clinical practice is both very limited and contradictory. As a consequence, the technique remains highly controversial. A review of the existing literature sheds light on patient- and treatment-related factors that may significantly affect both the effectiveness and the safety of the procedure. The current article discusses important aspects of key publications on the topic, offers suggestions for clinical practice, and highlights unmet needs that should be addressed by future research.

Vitreous and Vision Degrading Myodesopsia

Macromolecules comprise only 2% of vitreous, yet are responsible for its gel state, transparency, and physiologic function(s) within the eye. Myopia and aging alter collagen and hyaluronan association causing concurrent gel liquefaction and fibrous degeneration. The resulting vitreous opacities and collapse of the vitreous body during posterior vitreous detachment are the most common causes for the visual phenomenon of vitreous floaters. Previously considered innocuous, the vitreous opacities that cause floaters sometimes impact vision by profoundly degrading contrast sensitivity function and impairing quality-of-life. While many people adapt to vitreous floaters, clinically significant cases can be diagnosed with Vision Degrading Myodesopsia based upon echographic assessment of vitreous structure and by measuring contrast sensitivity function. Perhaps due to the ubiquity of floaters, the medical profession has to date largely ignored the plight of those with Vision Degrading Myodesopsia. Improved diagnostics will enable better disease staging and more accurate identification of severe cases that merit therapy. YAG laser treatments may occasionally be slightly effective, but vitrectomy is currently the definitive cure. Future developments will usher in more informative diagnostic approaches as well as safer and more effective therapeutic strategies. Improved laser treatments, new pharmacotherapies, and possibly non-invasive optical corrections are exciting new approaches to pursue. Ultimately, enhanced understanding of the underlying pathogenesis of Vision Degrading Myodesopsia should result in prevention, the ultimate goal of modern Medicine.

Cavitation induced by shock wave focusing in eye-like experimental configurations

During laser-induced, breakdown-based medical procedures in human eyes such as posterior capsulotomy and vitreolysis, shock waves are emitted from the location of the plasma. A part of these spherically expanding transients is reflected from the concave surface of the corneal epithelium and refocused within the eye. Using a simplified experimental model of the eye, the dominant secondary cavitation clusters were detected by high-speed camera shadowgraphy in the refocusing volume, dislocated from the breakdown position and described by an abridged ray theory. Individual microbubbles were detected in the preheated cone of the incoming laser pulse and radially extending cavitation filaments were generated around the location of the breakdown soon after collapse of the initial bubble. The generation of the secondary cavitation structures due to shock wave focusing can be considered an adverse effect, important in ophthalmology.

Laser-induced plasmon-mediated treatment of retinoblastoma in viscous vitreous phantom

Retinoblastoma (RB) is a rare form of cancer of the retina most prevalent in young children. We successfully show that laser-induced cell disruption, mediated by gold plasmonic nanoparticle (NP), is a potential and efficient therapy to kill the cancerous cells. The proof of concept is demonstrated in vitro on cultured Y79 RB cancer cells with a nanosecond laser at 527 nm, for both attached cells at the bottom of a Petri dish and for floating, clustered cells in a viscous vitreous phantom comprised of hyaluronan. We report a cellular death of 82% after irradiation in classic culture medium and a cellular death of 98% in vitreous phantom, for similar number of NPs in each sample. It is found that the NPs efficiently penetrate the floating Y79 clusters cells in the vitreous phantom, leading to a cellular death of over 85% even within the centre of the aggregates. The proposed treatment technique is based on a similar nanosecond laser used to eliminate floaters in the vitreous, but with much lower (100-1000 times) fluences of 20 J cm^-2 .

[Evaluation of YAG-laser vitreolysis effectiveness based on quantitative characterization of vitreous floaters]

PURPOSE

To develop methods for evaluating effectiveness of YAG-laser vitreolysis of vitreous floaters.

MATERIAL AND METHODS

The study included 144 patients (173 eyes) who had underwent YAG-laser vitreolysis and were under observation from 01.09.16 to 31.01.18. The patients were 34 to 86 years old (mean age 62.7±10.2 years), 28 (19.4%) patients were male, 116 (80.6%) - female. All patients underwent standard and additional examination: ultrasonography (Accutome B-scan plus, U.S.A.), optic biometry (Lenstar 900, Haag-Streit, Switzerland), spectral optical coherence tomography using RTVue XR Avanti scanner (Optovue, U.S.A.) in modes Enhanced HD Line, 3D Retina, 3D Widefield MCT, Cross Line, Angio Retina, and scanning laser ophthalmoscopy (SLO) using Navilas 577s system. Laser vitreolysis was performed using the Ultra Q Reflex laser (Ellex, Australia).

RESULTS

This paper presents methods of objective quantitative and qualitative assessment of artifactual shadows of vitreous floaters with spectral optical coherence tomographic scanner RTVue xR Avanti employing an algorithm of automatic detection of non-perfusion zones in modes Angio Retina, HD Angio Retina, as well as foveal avascular zone (FAZ) measurement with Angio Analytics® software. SLO performed with Navilas 577s was used as method of visualizing floaters and artifactual shadows in retinal surface layers prior to surgical treatment and after YAG-laser vitreolysis.

CONCLUSION

Suggested methods of quantitative and qualitative assessment of artifactual shadows of the floaters in retinal layers are promising and may prove to be highly relevant for clinical monitoring of patients, optimization of treatment indications and evaluating effectiveness of YAG-laser vitreolysis. Further research of laser vitreolysis effectiveness in patients with vitreous floaters is necessary.

Indications for Q-Switched and Mode-Locked Nd: Yag Lasers in Vitreoretinal Pathology

The indications for two types of pulsed Nd: YAG lasers in the treatment of vitreous pathology are reviewed. A series of 94 eyes from 93 patients were treated with the mode-locked system and 72 eyes from 71 patients were treated with the Q-switched system. A classification of vitreous pathology with prognostic value for the efficacy of treatment of both lasers is established. For the Q-switched laser the range of indications in the posterior pole is larger and fewer sessions are needed; however, complications are more frequent than with the mode-locked laser. This difference is due to the higher energy needed with the Q-switched laser to treat more severe vitreous pathology.

Reported Complications Following Laser Vitreolysis

Importance

Use of laser vitreolysis for symptomatic floaters has increased in recent years, but prospective studies are not available and the complication profile is poorly understood.

Objective

To analyze cases of complications following laser vitreolysis as voluntarily reported to the American Society of Retina Specialists Research and Safety in Therapeutics (ASRS ReST) Committee, an independent task force formed to monitor device-related and drug-related safety events.

Design, Setting, and Participants

A retrospective assessment was performed of all cases of complications following laser vitreolysis that were voluntarily reported by practitioners throughout the United States to the ASRS ReST Committee from the first report on September 19, 2016, through March 16, 2017, the date of data analysis and manuscript writing.

Main Outcomes and Measures

Complications reported to the ASRS ReST Committee following laser vitreolysis were analyzed by type to gain an understanding of the spectrum of potential complications.

Results

A total of 16 complications following laser vitreolysis were reported in 15 patients by 7 US vitreoretinal specialists during the study period. Complications included elevated intraocular pressure leading to glaucoma; cataracts, including posterior capsule defects requiring cataract surgery; retinal tear; retinal detachment; retinal hemorrhages; scotomas; and an increased number of floaters.

Conclusions and Relevance

This report presents a spectrum of complications reported to the ASRS ReST Committee across 6 months. The rate of complications cannot be determined because the denominator of total cases is unknown. Also, these findings cannot determine whether there is a causal association between these complications and laser vitreolysis. Prospective studies are warranted to better understand the efficacy of this procedure and the frequency of attendant complications. Until then, practitioners should be aware of the profile of potential complications to properly inform patients during the consent process. The ASRS ReST Committee will continue to monitor device-related and drug-related adverse events and encourages active surveillance and reporting by all physicians.

Rapid Cataract Progression after Nd:YAG Vitreolysis for Vitreous Floaters: A Case Report and Literature Review

PURPOSE

We report a case of rapid cataract progression after Nd:YAG vitreolysis for vitreous floaters.

CASE REPORT

A 55-year-old man presented with acute onset of blurred vision following Nd:YAG vitreolysis for symptomatic floaters in the left eye. His initial best corrected visual acuity (BCVA) was 20/1,000 in the left eye. Ocular examinations showed frost-like opacities of the lens and a suspected break of the posterior capsule in the left eye. There were no detectable retinal lesions. Cataract surgery was then arranged. Posterior capsular rupture and vitreous loss occurred during surgery, which required a subsequent pars plana vitrectomy. After the surgery, BCVA in the left eye gradually improved to 20/20 and was maintained during a 1-year follow-up period.

CONCLUSION

Crystalline lens injuries and rapid cataract progression may occur following Nd:YAG vitreolysis. While dealing with this type of complicated cataract, clinicians should be aware of the possibility of posterior lens capsule rupture during surgery and the need for combined vitrectomy.

Manuel's asteroid disruption technique

A seventy-year-old male presented with dense asteroid hyalosis in both eyes. He had undergone cataract extraction in one eye 3 years ago, and the other eye had immature cataract. Both the autorefractor and dilated streak retinoscopy did not give readings and subjective visual improvement could not be achieved. Immediately following YAG posterior capsulotomy and anterior vitreous asteroid disruption, the vision improved to 20/20 with recordable auto refractor and streak retinoscopy values. Our initial experience indicates that the treatment is simple, safe and effective but needs controlled and prospective studies to confirm its long-term safety.

Cataract formation after YAG laser vitreolysis: importance of femtosecond laser anterior capsulotomies in perforated posterior capsules

PURPOSE

To report a patient who developed a white cataract after Nd:YAG laser vitreolysis with a posterior capsule defect.

METHODS

Femtosecond laser-assisted capsulotomy was performed for optic capture fixation in a patient with a cataract due to a posterior capsule defect after Nd:YAG laser-vitreolysis.

RESULTS

A 55-year-old, highly myopic woman presented with visual impairment 4 days after Nd:YAG laser vitreolysis due to preexisting floaters. The slit-lamp examination showed a mature white cataract; therefore, the intactness of the posterior capsule could not be judged. The patient underwent cataract surgery with femtosecond laser-assisted capsulotomy. Intraoperatively, a highly disrupted posterior capsule was observed. Intraocular lens (IOL) was implanted into the ciliary sulcus and the anterior circular and centered capsulotomy was used for posterior optic capture fixation. Then vitrectomy was performed. No intraoperative or postoperative complications occurred.

CONCLUSIONS

YAG laser vitreolysis presents a new and promising therapeutic approach for floaters. However, the complications are unknown. We describe the induction of cataract as a major complication. Furthermore, the femtosecond laser can ensure a circular and complete anterior capsulotomy, which is essential for optic capture fixation in these cases.

Vitrectomy for primary symptomatic vitreous opacities: an evidence-based review

Floaters are a common ocular condition which form as a consequence of aging changes in the vitreous. Although in most patients the symptoms are minimal, they can cause significant impairment in vision-related quality of life in a small population of patients. Recently there has been an increase in awareness of the visual disability caused by floaters, and the evidence-base for treatment of this condition using small-gauge vitrectomy has increased. In this review, we define the term 'floaters' as symptomatic vitreous opacities (SVO). We suggest a classification dependent on the presence or absence of posterior vitreous detachment and discuss their pathogenesis and natural history. We review their impact on patients' quality of life related to visual function. We review the psychological factors that may have a role in some patients who appear to be affected by SVO to the extent that they pursue all options including surgery with all its attendant risks. We summarise the available evidence-base of treatment options available for SVO with special emphasis on the safety and efficacy of vitrectomy for this condition.

Vitreous floaters: Etiology, diagnostics, and management

Vitreous is a hydrated extracellular matrix comprised primarily of water, collagens, and hyaluronan organized into a homogeneously transparent gel. Gel liquefaction results from molecular alterations with dissociation of collagen from hyaluronan and aggregation of collagen fibrils forming fibers that cause light scattering and hence symptomatic floaters, especially in myopia. With aging, gel liquefaction and weakened vitreoretinal adhesion result in posterior vitreous detachment, the most common cause of primary symptomatic floaters arising from the dense collagen matrix of the posterior vitreous cortex. Recent studies indicate that symptomatic floaters are not only more prevalent, but also have a negative impact on the quality of life that is greater than previously appreciated. We review the literature concerning management of symptomatic vitreous floaters, currently either with observation, vitrectomy, or Nd:YAG laser. Published evidence is consistent with a low-risk profile and excellent success rate for floater vitrectomy, particularly with sutureless small gauge instruments and a limited core vitrectomy without PVD induction. Nd:YAG laser treatment of floaters, reported less commonly, claims resolution of floaters ranging between 0% and 100%; however, both peer-reviewed literature and assertions on web-based nonpeer-reviewed laser vitreolysis sites remain to be substantiated, and at present only vitrectomy has proven value. Prospective studies using objective, quantitative outcome measures are required to assess the relative efficacy and safety of these two procedures as well as new therapies such as pharmacologic vitreolysis.

Ageing of the vitreous: From acute onset floaters and flashes to retinal detachment

Floaters and flashes are most commonly symptoms of age-related degenerative changes in the vitreous body and posterior vitreous detachment. The etiology and pathogenesis of floaters' formation is still not well understood. Patients with acute-onset floaters, flashes and defects in their visual field, represent a medical emergency with the need for same day referral to an ophthalmologist. Indirect ophthalmoscopy with scleral indentation is needed in order to find possible retinal break(s), on-time treatment and prevention of retinal detachment. The molecular and genetic pathogenesis, as well as the epidemiology of the ageing changes of the vitreous is summarized here, with view on the several treatment modalities in relation to their success rate and side-effects.

Refractory open-angle glaucoma after neodymium-yttrium-aluminum-garnet laser lysis of vitreous floaters

PURPOSE

To illustrate 3 cases of chronic open-angle glaucoma secondary to the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser vitreolysis procedure for symptomatic vitreous floaters.

DESIGN

Observational case series.

METHODS

Location of the study was the Doheny Eye Institute. Three eyes of 2 patients who developed chronic open-angle glaucoma after Nd:YAG vitreolysis for symptomatic floaters presenting with very high intraocular pressure (IOP >40 mm Hg) were selected. The time from the laser treatment to the onset of elevated pressure ranges from 1 week to 8 months. There was no associated inflammation, steroid use, or other identifiable cause of chronic IOP elevation.

RESULTS

All eyes were treated initially with glaucoma medication, followed by selective laser trabeculoplasty (SLT) and eventually glaucoma surgery (Trabectome) in 2 eyes for disease management. In all eyes, intraocular pressures were eventually stabilized within a normal pressure range from 18 to 38 months following Nd:YAG vitreolysis. At the latest follow-up post surgery, all eyes had intraocular pressures of 22 mm Hg or less with or without medications.

CONCLUSIONS

Secondary open-angle glaucoma is a complication of Nd:YAG vitreolysis for symptomatic floaters that may present with an increase in intraocular pressure immediately, or many months after the surgery. Furthermore this complication may be permanent and require chronic medical therapy or glaucoma surgery.

Current treatment for vitreous floaters

Vitreous floaters are a common complaint in the ophthalmic care setting. Patients seek explanation and advice regarding possible treatment options. Because the condition is considered benign, ophthalmic care practitioners have little to offer regarding treatment options. The majority of cases encountered are managed with patient education and reassurance. Although almost all patients accept the conservative management option, there is a small subset of patients who may desire a more aggressive treatment intervention for resolution of their visual symptoms. Information with regard to treatment options is readily available to patients through Internet searches and non-peer reviewed educational Web sites. The risks and benefits for these treatment options are not fully covered. Management of floaters should include education regarding "off-label" procedures as well as discussion about benefits and risks associated with such treatment options. It is vital that eye care practitioners advise and counsel patients with symptomatic floaters for optimum ocular health care. This article reviews the current conventional and "off-label" treatment options for symptomatic patients with vitreous floaters.

Argon Laser Photocystotomy of a Vitreous Cyst

Free-floating idiopathic vitreous cysts are rare entities. For symptomatic patients, treatment options include laser photocystotomy or pars plana vitrectomy (PPV) with cyst excision. Historically, size of the cyst impacted treatment approaches. Laser treatments have been used for smaller cysts ranging 3 to 5 mm in diameter. PPV has been utilized for cysts larger than 4 mm. Successful laser photocystotomy has been reported, utilizing both argon and Nd: YAG lasers. Herein, we present a case of successful argon laser photocystotomy of a 7.1 mm diameter vitreous cyst, the largest documented cyst ever treated. Treatment should be individualized based on patient age, ability to cooperate in an office setting, phakic status, status of the posterior hyaloid, cyst morphology, and location. In our case, because of pigment on the anterior cyst surface, and the presence of an attached posterior hyaloid, the argon green laser was used.

Triamcinolone-assisted neodymium:YAG laser vitreolysis

Triamcinolone acetonide was injected into the vitreous cavity to treat a case of cystoid macular edema. After the injection, slit-lamp examination was performed and the vitreous strands adhered to the remaining edge of the posterior capsule were clearly visualized. The strands were dissected with neodymium:YAG (Nd:YAG) laser shots. A technique that can be used to facilitate diagnosis and Nd:YAG laser dissection of vitreous strands in cases with complications of adhesion of vitreous strands into anterior segment structures is described.

Nd:YAG vitreolysis and pars plana vitrectomy: surgical treatment for vitreous floaters

PURPOSE OF STUDY

To determine the efficacy of Nd:YAG vitreolysis and pars plana vitrectomy in the treatment of vitreous floaters.

METHODS

This is a single centre retrospective study of 31 patients (42 eyes) who underwent 54 procedures, Nd:YAG vitreolysis or pars plana vitrectomy, for the treatment of vitreous floaters between January 1992 and December 2000. Main outcome measures were percentage symptomatic improvement following treatment and incidence of post-operative complications. Statistical analysis was performed using the Fisher exact test.

RESULTS

Posterior vitreous detachment was the primary cause of floaters in all 42 eyes with co-existing vitreous veils in three eyes and asteroid hyalosis in two eyes. Thirty-nine of 42 eyes received Nd:YAG vitreolysis. Thirty-eight percent found Nd:YAG vitreolysis moderately improved their symptoms while 61.5% found no improvement. After an average of 14.7 months follow-up no post-operative complications were recorded. Fifteen eyes underwent a pars plana vitrectomy, one with combined phacoemulsification and posterior chamber implantation and 11 following unsuccessful laser vitreolysis. Pars plana vitrectomy resulted in full resolution of symptoms in 93.3% of eyes. One patient developed a post-operative retinal detachment which was successfully treated leaving the patient with 6/5 VA.

CONCLUSION

Patients' symptoms from vitreous floaters are often underestimated resulting in no intervention. This paper shows Nd:YAG vitreolysis to be a safe but only moderately effective primary treatment conferring clinical benefit in one third of patients. Pars plana vitrectomy, while offering superior results, should be reserved for patients who remain markedly symptomatic following vitreolysis, until future studies further clarify its role in the treatment of patients with floaters and posterior vitreous detachment.

Neodymium:YLF picosecond laser segmentation for retinal traction associated with proliferative diabetic retinopathy

PURPOSE

To determine the applicability of laser segmentation for severing fibrovascular tissue and hyaloid interfaces in the treatment of tractional complications of proliferative diabetic retinopathy.

METHODS

A prototype neodymium:yttrium-lithium-fluoride (Nd:YLF) picosecond pulse photodisruptive laser was used in eight eyes (seven patients) with proliferative diabetic retinopathy as part of a Food and Drug Administration-approved phase 1 protocol. There were three indications for treatment: type I: distortion and shallow elevation of the macular caused by taut, adherent, posterior hyaloid interface (two eyes); type II: traction retinal detachment involving the fovea (two eyes); and type III: fovea-threatened, traction retinal detachment (four eyes). Traction release was accomplished by laser segmentation of the detached hyaloid interfaces and fibrotic, contracted proliferative tissue. The Nd:YLF uses low pulse energy (0.10 mJ, 1,000 pulses per second for 10 consecutive seconds) that allows tissue cutting near the retinal surface.

RESULTS

Both type I eyes had relief of traction forces; visual acuity improved from 20/400 to 20/50 in one eye; the other remained stable. Of the two type II eyes, one had anatomic reattachment of the fovea with improvement in visual acuity (hand movements to 20/50); the second required vitrectomy. Of the four type III eyes, all had anatomic improvement; three maintained pretreatment acuity; the fourth eye developed vitreous hemorrhage at 6 months and underwent vitrectomy. Three treatments (two eyes) caused vitreous hemorrhage that resulted in a transient drop in acuity (1 to 2 lines). No patient developed a retinal break or choroidal hemorrhage.

CONCLUSION

In a small pilot study, the Nd:YLF laser segmented proliferative tissue near the retinal surface and elevated hyaloid interfaces. In selected cases, this may enable flattening of traction retinal detachment or release of retinal distortion.

The correlation between excessive vitreal protein levels, prostaglandin E2 levels, and the blood retinal barrier

Changes in vitreal protein and prostaglandin E2 (PGE2) concentrations, as well as chorioretinal in vitro PGE2 production, were studied in rabbit eyes following Neodymium (Nd):YAG laser retinal exposure. Laser exposure was associated with an enhanced vitreal PGE2 concentration throughout a two-week observation period, with highest levels on days 1 and 7 after exposure (a 5.3 and 4.7 increase above baseline, respectively). A transitory 50% elevation above baseline in vitreal protein levels was observed in the laser-exposed eyes during the second week after exposure. Laser exposure was also associated with an enhancement in the in vitro chorioretinal PGE2 production, which varied throughout the observation period, and was more pronounced during the first week after exposure, when levels were four times higher than baseline. Initially PGE2 vitreal levels were closely related to excessive in vitro production. However, during the second week after exposure, evidence of such correlation was lacking, but PGE2 vitreal levels coincided with a small increase in vitreal protein levels. It is suggested that disruption of the blood retinal barrier by the long-term exposure to mildly elevated vitreal PGE2 levels was accountable for protein leakage, which might have affected PGE2 removal mechanisms.

Nd:YAG laser photodisruption of hemorrhagic detachment of the internal limiting membrane

We used a Q-switched Nd:YAG laser to create an opening in the internal limiting membrane in three eyes with hemorrhagic detachment of the internal limiting membrane. In all instances, after membranotomy blood was rapidly cleared from the preretinal space resulting in prompt improvement in visual acuity. No retinal injury was observed. Nd:YAG laser photodisruption may be useful in the treatment of some cases of subinternal limiting hemorrhages.