Microsporidial keratoconjunctivitis - first outbreak in Japan.

BACKGROUND: Most cases of microsporidial keratoconjunctivitis are found in the Southern hemisphere. Our purpose was to investigate the first outbreak of microsporidial keratoconjunctivitis in Japan among healthy, immunocompetent soccer players from the same team during a 1-month period. CASE PRESENTATION: This study is an observational case series. The medical records were analyzed for five cases with microsporidial keratoconjunctivitis who presented within September 2022. All five cases were males between 28 and 36 years old. These previously healthy individuals belonged to the same football team. Their eyes were considered susceptible to contaminated water or dirt from the turf at game and practice sites. All cases involved unilateral conjunctivitis, with scattered round white lesions that showed positive fluorescein staining in the corneal epithelium. All cases experienced diminution of vision in the affected eye. In three cases, direct smears showed spores of approximately 2-3 µm in diameter. Polymerase chain reaction (PCR) analysis of corneal scrapes revealed partial amplification of microsporidial 18 S ribosomal RNA gene in four cases. Sequences of PCR products from all four cases showed 100% identity with strains of Vittaforma corneae previously reported from an outbreak in Singapore. All cases were treated with topical therapy, including voriconazole, fluorometholone, and levofloxacin. Four eyes underwent corneal scraping. After treatment, all eyes healed without residual opacities. CONCLUSIONS: Only a few sporadic case reports of this disease have previously been reported in Japan. We detected V. corneae in our case series, representing what appears to be the first outbreak of microsporidial keratoconjunctivitis in Japan. Exposure to contaminated water or soil, in addition to inadequate sanitary facilities, represents a potential source of infection. Further investigations to clarify the characteristics of microsporidia seem warranted.

Whole Corneal Descemetocele.

Background and Objectives: To report a case of microbial keratitis complicated by severe corneal melting and whole corneal descemetocele. Methods: A 72-year-old male farmer presented with a right corneal ulcer involving nearly the entire cornea, which was almost completely melted down with the remaining Descemet's membrane (DM). The pupil area was filled with melted necrotic material, with the intraocular lens partially protruding from the pupil and indenting the DM. Corneal optical coherence tomography (OCT) examination revealed a corneal thickness of 37 µm that was attached to its back surface, with the iris and a part of the intraocular lens (IOL) protruding through the pupil. The patient was hospitalized and treated with local and systemic antibiotics until control of the inflammation was achieved. Corneoscleral transplantation plus excision/transplantation of the corneal limbus were performed, and the entire corneal limbus was lamellarly incised. After completely suturing all around the transplanted corneoscleral graft, the anterior chamber was formed. Postoperative treatment included local antibiotics, anti-inflammatory drugs, and cycloplegic drops. Results: There was no recurrence of infection, and the corneal epithelium gradually regenerated and covered the whole graft. Visual acuity was light perception at 6 months after the surgery. The patient was satisfied that the globe was preserved and did not wish to undergo any further treatment. Conclusions: Corneoscleral transplantation is preferred for the treatment of large-sized descemetoceles with active microbial keratitis and extensive infiltrates, especially in cases where the whole cornea has transformed into a large cyst.

Corneal damage and its recovery after instillation of preservative-free versus preserved latanoprost eye drops.

Purpose: Latanoprost ophthalmic solution is highly effective as a therapeutic agent for glaucoma and is applied worldwide. However, harmful effects on the corneal surface have been reported regarding the commercially available latanoprost ophthalmic solution. Corneal surface toxicity may be caused by the added preservative of the ophthalmic solution. In order to ascertain whether latanoprost itself can damage the cornea or if this is solely due to the added preservatives, this study attempted to determine the corneal changes that occur at different time periods following usage of preservative-free versus preserved latanoprost eye drops.Materials and methods: Preservative-free latanoprost eye drops (Monoprost®) or preserved latanoprost eye drops (Xalatan®) containing 0.02% benzalkonium chloride (BAC) were instilled in the corneas of rabbits. For each of the two different eye drop solutions, the rabbits used in this experiment were divided into three exposure groups: 1 minute, 24 hour, and 1 week groups. Corneal transepithelial electrical resistance (TER) and scanning electron microscopy (SEM) were examined immediately (1 minute) after instillation, at 24 hours after instillation, and at 24 hours after 1 week of daily instillations of latanoprost. Hank's balanced salt solution was used in the control group.Results: The mean corneal TER of the control group was 933.8 ± 279.0 Ω cm2. In preservative-free latanoprost instilled corneas, there was no significant decrease in the TER or morphological changes at any of the time points, with the relative TER values of 117 ± 38%, 100 ± 34%, and 93 ± 21% for 1 minute, 1 day, and 1 week time points, respectively. In preserved latanoprost instilled corneas, SEM showed that only the immediate group exhibited superficial cell damage and a significant decrease in the corneal TER compared to the controls and other time points and to the immediate preservative-free latanoprost corneas. In the preserved latanoprost groups, the relative TER values were 18 ± 5%, 110 ± 28%, and 92 ± 10%, for the three respective observation time points.Conclusions: Preservative-free latanoprost can be safely instilled to the corneal epithelium. Latanoprost with 0.02% BAC has an immediate deleterious impact on the corneal epithelium; however, it disappears within 24 hours after instillation.

Safety of sodium hyaluronate eye drop with C12-benzalkonium chloride.

PURPOSE: In this study, we investigated the effects of commercially available multi-dose sodium hyaluronate 0.1% (Hyalein®; Santen, Osaka, Japan) containing 0.003% C12-benzalkonium chloride (BAC) on the Corneal epithelium and its degree of safety. METHODS: Japanese white male rabbits were divided into four groups. The corneas of each group exposed to one of the following solutions: sodium hyaluronate 0.1%, C12-BAC, C12, 14, 16-BAC Mixture, and Hank's Balanced Salt Solution (HBSS) (as control), respectively. Corneal transepithelial electrical resistance (TER) changes after 60 s of exposure to the above solutions were measured in living rabbits. TER reflects the barrier function of the epithelium. In addition, scanning electron microscopy was used to examine the acute effects of the above solutions on the integrity of the corneal epithelium of four groups. RESULTS: There was no significant decrease in the corneal TER after exposure of the cornea to Hyalein® eye drops as compared to HBSS control eyes. Also, BAC mixture solution and C12-BAC did not produce any significant decrease in the corneal TER as compared to HBSS control eyes. All the corneal epithelium exposed to Hyalein®, 0.003% C12-BAC and 0.003% BAC mixture exhibited a regular appearance of the superficial cells with a high density of microvilli. CONCLUSION: This study confirms that Hyalein® has no acute hazardous effect on corneal epithelium.

Visual outcomes and prognostic factors in open-globe injuries.

BACKGROUND: Ocular trauma is an important cause of visual loss worldwide. Improvements in our knowledge of the pathophysiology and management of ocular trauma during the past 30 years, in conjunction with advances in the instrumentation and techniques of ocular surgery, have improved the efficacy of vitreoretinal surgery in injured eyes. The aim of the current study was to determine the visual outcomes and prognostic factors of open-globe injuries in the Japanese population. METHODS: Retrospective study of 59 eyes of 59 patients presented with open globe injuries between September 2008 and March 2014 at Nagasaki University Hospital was conducted. Demographic factors including age, gender, and clinical data such as cause of injury, presenting visual acuity (VA), location of injury, type of injury, lens status, presence of intraocular foreign body, types of required surgeries, and final VA were recorded. According to the classification of Ocular Trauma Classification Group, wound location was classified into three zones. Chi-square test was used to compare presented data. RESULTS: Out of the 59 patients, 46 were placed in the Light Perception (LP) group, and 13 were placed in the No Light Perception (NLP) group. Work-related trauma was the most common cause (27 eyes) followed by falls (19eyes). Work-related trauma was common in males (P = 0.004), while falls was significantly common in females (P = 0.00001). Zone III injuries had statistically significantly poor prognostic factor compared to other zones (P = 0.04). All cases of NLP group (100%) presented with rupture globe. Poor VA at first visit (P = 0.00001), rupture globe (P = 0.026), history of penetrating keratoplasty (PK) (P = 0.017), retinal detachment (RD) (P = 0.0001), vitreous hemorrhage (VH) (P = 0.044), and dislocation of crystalline lens (P = 0.0003) were considered as poor prognostic factors. CONCLUSION: Poor VA at first visit, rupture globe, zone III injuries, history of penetrating keratoplasty, RD, VH, and dislocation of crystalline lens were found to be poor prognostic factors. PPV had a good prognostic value in open globe injuries associated with posterior segment involvement.

Corneal Erosion With Pigments Derived From a Cosmetic Contact Lens: A Case Report.

PURPOSE: To report a case of corneal erosion with pigments derived from a cosmetic contact lens (CCL). METHODS: A 29-year-old woman complained of foreign body sensation after wearing CCL. Slit-lamp examination of her left eye revealed corneal erosion with yellow pigment at its edges. The surface of the CCLs was examined using the rub-off test and scanning electron microscopy (SEM). An elementary analysis using SEM with energy-dispersive x-ray (SEM-EDX) was also performed. RESULTS: On the back surface of the CCL, the pigments easily came off during the rub-off test. An SEM examination found exposed pigments with needle-like construction on the back surface. SEM-EDX revealed the presence of carbon, oxygen, iron, titanium, and chlorine in the pigments. CONCLUSION: Direct contact between the bare pigments on a CCL and the corneal surface can cause corneal damage.

Spontaneous dislocation of the posterior chamber intraocular lens.

AIM: To evaluate the possible risk factors for posterior chamber intraocular lens dislocation either in-the-bag (ITB) dislocation or out-of-the-bag (OOTB) dislocation. METHODS: All subjects who sustained late intraocular lens dislocation from January 2011 until May 2014 and presented to the Nagasaki University Hospital were included in the study. This study is a retrospective evaluation of all cases of posterior chamber intraocular lens dislocation in this defined period. All cases had history of uncomplicated cataract surgery with implantation of posterior chamber intraocular lens. Patients with history of trauma (before cataract surgery) were excluded from the study. The main outcome measures of the study were evaluation of risk factors for dislocation of both groups and determination of the interval between cataract surgery and dislocation. RESULTS: Thirty-six eyes (69.23%) suffered ITB dislocation, and 16 eyes (30.77%) suffered OOTB dislocation. Intraocular lens dislocation was common in males (42 eyes = 80.77%) than females (10 eyes = 19.23%). Patients of ITB dislocation group were significantly older than OOTB dislocation group at the time of initial intraocular lens implantation and at the time of exchange surgery. CONCLUSION: The most prevalent risk factors in both groups were axial myopia in 18 eyes (34.61%), vitreoretinal surgery in 16 eyes (30.77%), and pseudoexfoliation in 13 eyes (25%) in all cases.

Acute Corneal Toxicity of Diquas.

AIM: This study aimed to investigate acute corneal toxicity of commercially available diquafosol 3% ophthalmic solution (Diquas®), which contains C12 benzalkonium chloride (BAC) as a preservative. METHODS: Corneal transepithelial electrical resistance (TER) changes after a 60-second exposure to Diquas® (diquafosol 3% preserved with 0.0075% C12 BAC); 0.0075% C12 BAC and 0.0075% C12, C14, C16 BAC mixture were measured in living rabbits. Corneal damage was also examined by scanning electron microscopy (SEM). Hank's balanced salt solution (HBSS) was used as a control. RESULTS: Diquas® and 0.0075% C12 BAC did not produce any significant decrease in the corneal TER as compared to the HBSS control eyes. There was a significant decrease in the corneal TER after exposure of the cornea to the 0.0075% C12, C14, C16 BAC mixture (p < 0.01). SEM revealed that the superficial cells of the corneas exposed to the 0.0075% BAC mixture were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to Diquas® or 0.0075% C12 BAC appeared normal and had normal microvilli under SEM examinations. CONCLUSION: The acute corneal toxicity of Diquas® is less than that of the 0.0075% BAC mixture. Diquas® preserved with 0.0075% C12 BAC did not show acute corneal toxicity.

Acute corneal toxicity of latanoprost with different preservatives.

PURPOSE: To investigate the corneal toxicity of Xalatan and three latanoprost generics using transepithelial electrical resistance (TER) and scanning electron microscopy (SEM). METHODS: Corneal TER changes after a 60-s exposure to Xalatan (latanoprost 0.005% preserved with 0.02% BAC), and latanoprost generics (Latanoprost PF BAC free, Latanoprost Nitten SB containing sodium benzoate and Latanoprost Towa containing 0.01% BAC with sodium chloride polysorbate 80 as additive) were measured in living rabbits. Corneal damage was also examined by SEM. Hank's balanced salt solution (HBSS) was used as a control. RESULTS: There was a significant decrease in the corneal TER after exposure of the cornea to Xalatan (p < 0.01) and all latanoprost generics (p < 0.01: Latanoprost PF, p < 0.05: Latanoprost Nitten SB, Latanoprost Towa) as compared to HBSS. All latanoprost generics showed less TER decrease in the corneal TER as compared to Xalatan (p < 0.01). SEM revealed that superficial cells of Xalatan-treated corneas were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to HBSS or all latanoprost generics appeared normal and had normal microvilli under SEM examinations. CONCLUSION: The corneal toxicity of Xalatan is greater than that of latanoprost generics. Xalatan contains 0.02% BAC, which may be responsible for the corneal toxicity.

Comparison of rabbit corneal changes during different preservation techniques using optisol-GS and airlift.

A previous study suggested that the airlift condition is superior to the Optisol-GS condition for preserving the limbal tissue of the human cornea. The purpose of this research is to investigate a new preservation device that preserves the cornea while separating epithelial and endothelial areas. The differences after preserving the corneal epithelium under different conditions were compared. A total of 24 corneas of New Zealand rabbits were divided into four groups in which the corneal epithelia were submersed in Optisol-GS or under airlift conditions for 1 and 2 weeks at 4 [Formula: see text]C. Transparency, optical coherence tomography (OCT), hematoxylin and eosin (H &E) staining, and epithelial migration tests were used to assess corneal status. The epithelial migration examination showed significantly greater migration ability after the airlift condition. Corneas in the 1-week Optisol-GS group were the most transparent, followed by the 1-week airlift group. OCT showed a progressive increase in corneal thickness to the end of the study. H &E staining showed that the epithelial cells retained intact cellular structure and morphology of the cells for both 1-week-preserved groups. However, there was disruption of the corneal epithelial cell structure for both 2-week-preserved groups. Corneal epithelium preserved under the hypothermic airlift condition was comparable to that under the Optisol-GS condition.

Effectiveness of a photoscreener in identifying undiagnosed unilateral amblyopia at vision screening of 3-year-old children in Japan.

PURPOSE: In Japan a basic preparatory ophthalmic examination is routinely performed for 3-year-old children. This study aimed to determine the value of incorporating a photoscreener into the examination and evaluate parents' satisfaction with the photoscreener examination. STUDY DESIGN: Prospective study. METHODS: Children aged 42-47 months in Nagasaki City, Japan, underwent a visual acuity test by a parent at home and by automated vision screening using a photoscreener at their local municipal health center between October 2018 and March 2019. Subjects were children referred to Nagasaki University Hospital for examination after failing either test. Children previously diagnosed with strabismus and/or amblyopia were excluded. A questionnaire survey evaluated the level of satisfaction with the photoscreener-based screening by parents who attended these examinations at the local municipal health center. RESULTS: Of children who completed the two tests, 52 (failed visual acuity test, 3; failed photoscreener examination, 49) were referred for examination. Of the 49 photoscreener failures, 12 were diagnosed with amblyopia: unilateral amblyopia with anisometropic hyperopia in 10 (83.3%), and bilateral amblyopia with astigmatism and hyperopia in 2 (16.7%). The photoscreener detected all 12 cases of amblyopia, whereas the home-based visual acuity test detected only two cases. More than 80% of 1035 parents were satisfied with the photoscreener examination. CONCLUSION: Unilateral amblyopia with anisometropic hyperopia was easily overlooked with the home-based test but was detectable by photoscreener examination. The photoscreener proved to be an effective screening tool for amblyopia in children and was considered a satisfactory examination by a high proportion of parents.

Conjunctival Sac Microbiome in Infectious Conjunctivitis.

Acute bacterial conjunctival infections are common, and this study identified the conjunctival bacterial community in infectious conjunctivitis cases seen at the outpatient clinic of Khanh Hoa General Hospital in Nha Trang, Vietnam from October 2016 through December 2017. Conjunctival swabs were collected and tested using conventional culture, PCR, and 16S ribosomal RNA sequencing. The study included 47 randomly selected patients. More than 98% of all DNA reads represented five bacterial phyla. Three of these phyla constituted 92% of all sequences (Firmicutes (35%), Actinobacteria (31%), and Proteobacteria (26%)). At the genus level, there were 12 common genera that constituted about 61% of all sequence reads. Seven of those genera were common (Streptococcus (10%), Cutibacterium (10%), Staphylococcus (7%), Nocardioides (7%), Corynebacterium 1 (5%), Anoxybacillus (5%), and Acinetobacter (5%)), which encompassed 49% of all reads. As for diversity analysis, there was no difference on PERMANOVA analysis (unweighted UniFrac) for sex (p = 0.087), chemosis (p = 0.064), and unclassified eyedrops (p = 0.431). There was a significant difference in cases with bilateral conjunctivitis (p = 0.017) and for using antibiotics (p = 0.020). Of the predominant phyla, Firmicutes had the highest abundance in bacterial conjunctivitis in this study. Pseudomonas as a resident commensal microbiota may have an important role in the prevention of infection.

Prevalence of Streptococcus pneumoniae in conjunctival flora and association with nasopharyngeal carriage among children in a Vietnamese community.

Conjunctival pneumococcal serotypes among members of a community have not been investigated well. We determined the prevalence and association of Streptococcus pneumoniae in the nasopharynx and conjunctiva among children in a community before pneumococcal conjugate vaccine introduction. In October 2016, conjunctival and nasopharyngeal swabs were collected from children (< 24 months old) and nasopharyngeal swabs from mothers in Nha Trang, Vietnam. Quantitative lytA PCR and DNA microarray were performed to detect and serotype S. pneumoniae. The association between S. pneumoniae in the nasopharynx and conjunctiva was evaluated using multivariable logistic regression model. Among 698 children, 62 (8.9%, 95% CI 6.9-11.2%) were positive for S. pneumoniae in the conjunctiva. Non-encapsulated S. pneumoniae were most commonly identified, followed by serotypes 6A, 6B, and 14. Nasopharyngeal and conjunctival detection were positively associated (aOR 47.30, 95% CI 24.07-92.97). Low birth-weight, day-care attendance, and recent eye symptoms were independently associated with S. pneumoniae detection in the conjunctiva (aOR 11.14, 95% CI 3.76-32.98, aOR 2.19, 95% CI 1.45-3.31, and aOR 3.59, 95% CI 2.21-5.84, respectively). Serotypes and genotypes in the conjunctiva and nasopharynx matched in 87% of the children. Three mothers' nasopharyngeal pneumococcal samples had matched serotype and genotype with their child's in the conjunctiva and nasopharynx. S. pneumoniae presence in nasopharynx and conjunctiva were strongly associated. The high concordance of serotypes suggests nasopharyngeal carriage may be a source of transmission to the conjunctiva.

Intraocular deposits and cataracts after long-term rifabutin intake: A case report.

RATIONALE: Rifabutin is a broad-spectrum antibiotic known to cause deposits on the corneal endothelium and lens. We report a patient in whom cataracts developed and progressive pigment deposits were seen on the corneal endothelium, lens, and iridocorneal angle. PATIENT CONCERNS: The patient was a 45-year-old woman who had been received long-term treatment with a combination of various anti-mycobacterial drugs for multidrug-resistant tuberculosis starting in 2004. Rifabutin was started in 2009, and she was referred to our department in 2017 for detailed ophthalmological examination. DIAGNOSES: Both eyes showed pigmented deposits over the entire corneal endothelium, the entire periphery of the iridocorneal angle, and the anterior surface of the lens. Mild cataracts were also diagnosed bilaterally. Pigment deposits on the anterior surface of the lens and the cataracts in both eyes gradually progressed. These lesions were assumed to be associated with long term rifabutin intake. INTERVENTIONS: Rifabutin intake was discontinued after progression of intraocular deposits, cataracts, and ERG deterioration. OUTCOMES: Visual acuity improved, although cataracts, deposits, and ERG deterioration remained. LESSONS: Rifabutin may induce not only corneal endothelial deposits, but also cataracts and iridocorneal angle deposits.

Three cases of acute sterile corneal melt after cataract surgery.

PURPOSE: To report three cases of acute sterile corneal melt after cataract surgery. OBSERVATIONS: Case 1 was a 21-year-old male presenting with a corneal perforation of his right eye at 10 days after cataract surgery. Case 2 was a 67-year-old male who developed a corneal melt in his left eye at 15 days after cataract surgery. Case 3 was a 70-year-old female with a corneal melt of her left eye at 7 days after cataract surgery. None of the cases exhibited any signs of infection. Topical nonsteroidal anti-inflammatory drug use, dry eye, systemic autoimmune diseases, and/or a combination of these were present in patients who developed corneal melt after cataract surgery. CONCLUSIONS AND IMPORTANCE: Corneal melt cases can occur early after cataract surgery, thereby leading to corneal thinning and perforation.

Oral kallidinogenase improved visual acuity and maintained chorioretinal blood flow levels after treatment for diabetic macular edema.

PURPOSE: This study was designed to investigate the therapeutic effects of oral kallidinogenase medication as an adjuvant therapy in treating patients with diabetic macular edema (DME). STUDY DESIGN: This was a prospective, open-labeled, randomized study. METHODS: All patients were given posterior sub-Tenon triamcinolone acetonide (STTA) injection and focal laser treatment session for DME. The patients were subdivided into two groups: 1) those treated with oral kallidinogenase for at least 6 months after local treatment (treated group) and 2) those treated without oral kallidinogenase (untreated group). In this study, best-corrected visual acuity (BCVA), central retinal thickness (CRT), subfoveal choroidal thickness (SCT), and chorioretinal blood flow level were measured in 17 patients (19 eyes). Chorioretinal blood flow levels at the disc and macula were measured by laser speckle flowgraphy and evaluated using the mean blur rate (MBR). These data were measured at baseline and at 1, 3, and 6 months after treatment initiation. RESULTS: BCVA at 6 months after treatment significantly improved in treated group (P<0.05). But the mean CRT after treatment significantly decreased in both groups. There was no significant difference in the mean SCT at baseline between the two groups. The mean SCT after treatment in treated group was significantly thinner than that before treatment (P<0.05). Compared to baseline (100%), MBR at the disc and the macula at 6 months after treatment significantly decreased to 84.8% and 86.2%, respectively, in untreated group (P<0.05), though it remained unchanged at 98.7% and 99.7% in treated group. CONCLUSION: Oral kallidinogenase medication is useful as an adjuvant therapy to enhance the therapeutic effect of STTA in DME patients.

First experience of nDSAEK with heads-up surgery: A case report.

PURPOSE: To report a case of non-Descemet Stripping Automated Endothelial Keratoplasty (nDSAEK) using heads-up surgery. CASE/INTERVENTION: The case was a 72-years-old man who had history of left eye blunt trauma since childhood. One year ago, the patient was diagnosed to have left posttraumatic bullous keratopathy. The patient underwent lt nDSAEK by using the heads-up three-dimensional (3D) system last July. The surgery was performed with a Rescan 700 surgical microscope (Carl Zeiss), which is integrated with intraoperative optical coherence tomography (iOCT) system. During surgery, the surgeon and audience wore 3D passive polarized glasses. A 42 inch high-definition (HD) display and 2 HD cameras (Sony) were used. With this 3D system, the nDSAEK procedure before the graft insertion into the anterior chamber was easy especially with available high magnification. Also, using iOCT of the system enables the surgeon to detect any residual fluid at the donor graft-recipient interface and locate its place to be drained. The only disadvantage of the system was the difficulty in the detection of nDSAEK graft depth in the anterior chamber, which required frequent focus change during the surgery. Although the surgeon frequently adjusted the focus for clear stereoscopic view of the graft, he did not feel any eye strain or discomfort. All other steps of the procedure were performed without any problem and postoperative course of the patient was good. CONCLUSION: Using heads-up surgery for performing anterior segment surgeries is encouraging and promising.

Evaluation of retinal blood flow before and after panretinal photocoagulation using pattern scan laser for diabetic retinopathy.

PURPOSE: Laser speckle flowgraphy (LSFG) can measure blood flow in the ocular fundus. We analyzed the relationship between retinal blood flow and panretinal photocoagulation (PRP) in diabetic retinopathy. METHODS: This retrospective observational study examined the eyes of 35 patients with proliferative diabetic retinopathy (PDR) or non-PDR (NPDR). PRP was performed using a pattern scan laser. Using LSFG, blood flow was evaluated as the mean blur rate (MBR) or the relative flow volume (RFV). We also evaluated MBR in the vessels of the optic nerve head (MBR-V), RFV at the first retinal artery (RFV-A), and RFV at the first retinal vein (RFV-V) before bifurcation. Blood flows were measured prior to treatment initiation, during each PRP session, and after PRP. RESULTS: The total number of laser spots created was 4258 ± 461. Regression of neovascular activity at 6 months after PRP occurred in 29 (82.85%) eyes. MBR-V significantly decreased to 83.9 ± 16% (p = .0039), 79.3 ± 21% (p = .0001), and 73.5 ± 26% (p = .0001) after the first, second, and third PRP treatment sessions. MBR-V was also reduced to 75.0 ± 25% (p = .0001), 75.0 ± 25% (p = .0001), and 80.3 ± 22% (p = .0001) at 1, 3, and 6 months following PRP. During and at 6 months after the PRP treatments, RFV-A and RFV-V were also significantly reduced (p< .01). CONCLUSIONS: During and after PRP treatments using pattern scan laser, retinal blood flow was reduced. Retinal blood flow may be an auxiliary measurement for effectively evaluating PRP or PDR.