Translumental Nd:YAG Laser Embolysis for the Treatment of Branch Retinal Artery Occlusion

doi:10.21203/rs.3.rs-2112426/v1

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Translumental Nd:YAG Laser Embolysis for the Treatment of Branch Retinal Artery Occlusion

https://doi.org/10.21203/rs.3.rs-2112426/v1

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Objective

To investigate the clinical effect of translumental Nd:YAG laser embolysis(TYE) in the treatment of branch retinal artery occlusion(BRAO) for the patients with initial best corrected visual acuity(BCVA) no more than 20/100 and more than 24 hours from onset to visit.

Material and Methods

In this study, a total of 8 affected eyes(8 patients, 5 male and 3 female)with sight-threating BRAO received TYE therapy. All patients had a visible embolus within the affected eye. The mean age of the patients was 75.4 ± 6.3 years (range, 66–85 years). All the time from onset to initial visit to our hospital was more than 24 hours. The mean treatment time from onset were 7.4 ± 4.1 days (range, 2–14 days). Before the TYE treatment, the BCVA of all affected eyes was 20/100 or worse. All patients underwent BCVA test, fundus photography, optical coherence tomography(OCT), and central visual field(CVF) examination from the first to final visit.

Results

After the TYE treatment, all the cases showed immediate recovery of blood flow in the occluded branch retinal artery. The reperfusion of the blocked artery was observed in all affected eyes by fundus examination and fundus photography. The diameter of the affected branch retinal arteries increased significantly. The BCVA improved significantly by a average of 5.7 lines(rang 1–11 lines) in all patients. The BCVA of the affected eyes at the last follow-up were significantly improved compared before TYE treatment(P < 0.01). Before treatment the average MS was 11.2 ± 2.51, the average MS at the last follow-up time was 11.7 ± 3.55. There was no statistically significant difference in mean MS between pretreatment and at the last follow-up(P > 0.05). During the TYE treatment, mild retinal and vitreous hemorrhage usually happened which gradually absorbed in no more than 2 weeks.

Conclusion

Translumental Nd:YAG laser embolysis may be a safe and effective method to significantly improve the prognosis of BRAO in patients with initial BCVA no more than 20/100 and more than 24 hours from onset to visit.

translumental Nd:YAG laser embolysis

branch retinal artery occlusion

central retinal artery occlusion

The visual prognosis of BRAO is relatively favorable compared with central retinal artery occlusion(CRAO)^[1]. Ros MA et al^[2] reported that BRAO patients had a good natural course of disease, and more than 80% patients could recover to 0.5 or above visual acuity(VA). However, it was strongly associated with initial VA and the time from onset to visit the hospital. Hayreh et al^[3,4] reported that 79% of patients acquired VA improvement within 7 days from onset, but only 3% of patients acquired VA improvement after 7 days from onset. Mason et al^[5] reported that BRAO with initial VA of 20/40 or better usually remained at 20/40 or better and BRAO with poor VA of 20/100 or worse generally showed no significant improvement reported. Muramatsu et al^[6] reported that 92% of the patients could obtain improved VA, and 75% of them had BCVA of over 20/40 with only conventional treatment within 24 hours from the onset of symptoms, but there was no difference in the patients who visited the hospital after 24 hours from onset. Therefore, some treatment may be needed to improve the visual outcome of BRAO especially for the patients with poor initial visual acuity and relatively long time from onset to initial visit. It has been reported^[7,8] that the translumenal Nd:YAG laser embolysis(TYE) seemed to improve the visual function in BRAO. In particular, patients with poor VA benefit more^[9]. This study aimed to preliminarily evaluate clinical efficacy and the safety of TYE for BRAO. The purpose of this study was to preliminarily evaluate the efficacy and safety of TYE therapy in BRAO with poor initial vision(≤ 20/100) and with more than 24 hours from onset to visit.

2.1 Study Design and Participants. This non-randomized, monocentric, retrospective study reviewed 8 eyes of 8 patients with BRAO who visited Shanghai Shidong Hospital from January 2019 to January 2022. The study was adhered to the tenets of the Declaration of Helsinki and approved by the institutional review board of our hospital, our ethical batch number was 2022-007-01. Written informed consent was approved by all participants.

The inclusion criteria were as follows:

1 A branch retinal artery occlusion was diagnosed.

2 There was ablocked branch arteries in which the emboli could be observed.

3 The initial visual acuity of the affected eye ≤ 20/100.

4 The time from on set to visit ≥ 24 hours.

The exclusion criteria were as follows:

1 The patient had acute ocular surface inflammation and the contact lens counld not be used.

2 The patient had severe cataracts and vitreous opacities that affected laser therapy.

3 The patient did not sign the informed consent.

The patients were 5 men and 3 women. The mean age was 75.4 ± 6.3 years (range, 66–85 years). The mean time from onset of the disease to visit our hospital was 7.4 ± 4.1 days(range, 2–14 days).All the 8 patients had hypertension, 5 had hyperlipidemia, 6 had type 2 diabetes mellitus, 6 had carotid artery stenosis, and 5 had uremia(Table 2). The patients were followed up at 1 day, 2 weeks, 2–3 months, and the last visit after the TYE teatment. The BCVA tested by international standard visual acuity chart, fundus photography, OCT and CVF examination by Octopus 900 were examined before the TYE treatment and at every follow-up time. The CVF were statically analyzed by mean sensitivity(MS).

2.2 Surgical Technique. After the patient was given full pupil dilation, we used the laser equipment of Zeiss YAG Ⅲ. At first Nd:YAG laser was focused onto the distal part of the embolus by a Goldman three mirror contact len. At the beginning the laser is fired at 0.3mJ, and if the emboli is unchanged, it is fired in increments of 0.2mJ each time until the emboli breaks, then it is fired toward the proximal part of the emboli until the blocked branch artery was reperfused with blood flow. The average power of the laser is 1.5 ± 0.6mJ(range: 0.8–2.1mJ).

2.3 Statistical Analysis. Measurement data were expressed as X ± S. BCVA before treatment and at the last follow-up were compared using the t-test. Statistical analysis were performed using SPSS 17.0. Statistical significance was set at p < 0.01.

The rupture or movement of retinal artery emboli was found in all patients during the TYE treatment, the diameter of occlusive artery was immediately enlarged(Figure 1). The second day after treatment, most of the patients reported a significant improvement in visual acuity. The average of BCVA at the last follow-up after treatment was significantly improved compared with that before treatment (t = 4.070 P < 0.01)(Table 1). At the last follow-up BCVA was improved in all of 8 patients. Three or more lines of improvement were noted in 7/8(87.5%) patients. Five or more lines of improvement were noted in 75%(6/8) patients. Four of the patients(50%) gained 7 or more lines of improvement. Before treatment the average MS was 11.2 ± 2.51, the average MS at the last follow-up time was 11.7 ± 3.55. There was no statistically significant difference in mean MS between pretreatment and at the last follow-up(P > 0.05). The visual field defect still remained in the corresponding branch artery occlusion area at the last follow-up.

Table 1

The general condition of the patients and the visual acuity changes before and after treatment
Sequence	Gender^a	Age(y)	Treatment time since onset(d)	Hightest pulse energy(mJ)	Onset VA^b	Final VA^b	Time of follow-up(m)
1	m	77	2	1.8	1.22	0.10	6
2	m	81	12	2.1	0.82	0.52	4
3	m	71	8	1.5	1.00	0.30	2
4	f	85	14	1.6	1.70	0.10	6
5	f	76	7	1.8	0.82	0.70	4
6	m	78	3	2.0	0.82	0.30	3
7	m	69	6	2.1	0.92	0.40	3
8	f	66	7	1.6	1.85	0.30	4
a: m is male; f is female

b: Values are in LogMAR

Table 2

the systemic medical conditions of 8 patients
Systemic conditions	Number	Ratio
hypertension
Positive	8	100% (8/8)
negative	0	0% (0/8)
hyperlipidemia
Positive	5	62.5% (5/8)
negative	3	37.5% (3/8)
Diabetes mellitus
Positive	6	75% (6/8)
negative	2	25% (2/8)
Significant carotid stenosis
Positive	6	75% (6/8)
negative	2	25% (2/8)
Uremia
Positive	5	62.5% (5/8)
negative	3	37.5% (3/8)
Age > 70
Positive	5	62.5% (5/8)
negative	3	37.5% (3/8)

BRAO (CRAO) is common in ophthalmic emergencies. The incidence of symptomatic BRAO is about 30% that of central retinal artery occlusion(CRAO)^[10]. The incidence of CRAO is 1.9 per 100,000 person-years in the United States^[11], and the incidence rises to 10.1/100000 person-years in human beings that > 80 years of age^[12].

Currently there are no standard guidelines for the treatment of symptomatic BRAO(CRAO). Conventional conservative treatment such as digital ocular massage, anterior chamber paracentesis, acetazolamide, mannitol, topical anti-glaucoma and vasodilatory agents, and hyperbaric oxygen that have no Level I data to support any single therapy^[13]. The optimal use, risks, and effects of relatively aggressive intra-arterial and intravenous thrombolytic drugs have not been determined^[14,15].

In the natural history of all subtypes of CRAO including BRAO, there can be spontaneous improvement in VA and visual fields within the first 7 days after onset. However, after 7 days, the likelihood of further improvement was extremely low^[1,2]。In this study, the time from onset to visit was more than 24 hours for all 8 patients, and the time from onset to visit was more than 7 days for 4 patients, and the longest time was 14 days. All of them had significantly improved visual acuity after TYE treatment. This suggests that TYE treatment also has a good effect on BRAO patients with a long time from onset to visit.

The TYE treatment for BRAO is relatively difficult, compared with the Nd:YAG laser for the treatment of posterior cataract opacity and laser peripheral iridectomy, it is needed to carefully target the white embolus in the blocked branch artery. If the patient's initial vision acuity is relatively good, the TYE treatment may not be considered(Fig. 2). During the teatment the contact lens should not press the cornea hard, only lightly contact with the cornea to facilitate the focus. Because BRAO patients are all elderly, the head often moves slightly and unconsciously with the breath during the TYE treatment. The treatment should wait for the patient's breathing to be stable, and laser shooting should be carried out after finding the patient's breathing rhythm. This is done to prevent accidental injury to the retina of the patient, which is similar to the macular grid photocoagulation. The Nd:YAG laser is focused at 4 points, it is possible that the 4 points can not be focused at one point. This situation may be caused by the contact len pressing the patient's corea too hard or the contact lens may be slightly tilted. After correcting these errors, the laser can generally focus in one point at the embolus. If the aiming light is always unable to focus in one point, it may be caused by the high astigmatism of the patient. In this case, three-point or two-point focusing can be carried out instead of Four-point focusing. We suggest starting with the distal part of the embolus to prevent retinal bleeding. When the embolus is completely broken and flushed to the distal end of the artery, blood flow in the blocked artery can be clearly seen and the diameter of the blocked artery can be enlarged.

The patients in this study were unable to undergo FFA before TYE treatment due to some serious basic diseases, such as uremia, serious hypertension, anaphylactic constitution, excessive mental stress and anxiety. BRAO can be diagnosed through the history inquiry and fundus examination, and the location of emboli can be easily found through fundus examination. BRAO is an ophthalmic emergency. In order to treat it as early as possible, we immediately treated it with TYE as soon as the diagnosis of BRAO was clear. FFA is usually not used in the diagnosis of retinal artery occlusion due to its long time consuming ^[16,17].

Muramatsu et al^[6] reported that hyperlipidemia was related to a poor prognosis of BCVA in BRAO patients. In our study, all 8 patients had hypertension; There were 5 patients with hyperlipidemia (62.5%, 5/8). 6 patients (75%, 6/8) had type 2 diabetes; 6 patients (75%, 6/8) had significant carotid stenosis. Five patients had uremia caused by type 2 diabetes required blood purification treatment(62.5%, 5/8). All patients had initial visual acuity ≤ 20/100(Table 2). We speculate that patients with systemic diseases such as hypertension, diabetes, hyperlipidemia, carotid artery stenosis and renal failure are more likely to suffer from vascular embolism diseases. If BRAO is diagnosed, they should be treated more aggressively (such as TYE treatment) because of their poor visual prognosis.

Risk factors for BRAO have not been reported in the literature. We can learn from reports about risk factors for CRAO. Anderson et al reported^[18] that CRAO was closely related to ipsylateral internal carotid artery stenosis. Patrick et al reported^[19] that 37% of 103 CRAO patients had iplateral carotid stenosis. The European Assessment Group for Lysis in The Eye (EAGLE) Study^[20] reported that 31 of 77 CRAO patients (40%) had carotid artery stenosis ≥ 70%. EAGLE reported that cardiovascular factors contributing to the high incidence of CRAO include obesity (82%), hypertension (73%), hyperlipidemia (49%) and diabetes (14%). As TYE is a local treatment for ophthalmology, it cannot eliminate the risk factors of patients. During the follow-up, we suggest patients to go to the internal medicine department to control their risk factors to prevent recurrence of RAO. No recurrence of RAO was observed in the 8 patients in this study during follow-up.

We were concerned about the possibility of retinal ischemia reperfusion injury^[21] after the blood flow of the embolized branch artery was restored by TYE, but it was found that the visual acuity of all patients recovered well, and there was no aggravation of retinal edema on OCT after treatment. we speculate that there may not be clinically obvious ischemia-reperfusion injury after TYE treatment for BRAO.

After laser treatment, the visual field function did not recover significantly in the corresponding retinal area with the original branch artery occlusion. The recovery of visual field was far worse than that of central visual acuity. The possible reason is that the central area of the macula is mainly supplied by the choroid, the photoreceptor cells are less affected by ischemia, and TYE treatment can relieve the edema of the macular area, thereby rapidly improving visual acuity. However, in the area of branch artery occlusion in the peripheral retina, the inner retinal layer is only supplied by the retinal artery, so the visual field recovery is poor.

In this study, the prognosis of visual acuity after treatment was significantly better than that of the natural course of disease, suggesting that The TYE treatment could be more beneficial to the recovery of visual acuity. This study was a retrospective study with a small number of cases, and more clinical data are needed to confirm whether it is truly superior to the natural course of disease.

Ethics approval and consent to participate

All methods were carried out in accordance with relevant guidelines and regulations or Declaration of Helsinki. This research article was approved by the ethics committee of shidong hospital, yangpu district, Shanghai. The ethical approval number is 2022-007-01.

Consent to publish

The authors declare that the written consent to publish this article was obtained from the all study participants and the patient gave written consent to the authors for her personal or clinical details to be published in this study.

Availability of data and materials

All data generated or analysed during this study are included in this published article.

Competing interests

The authors declare that they have no competing interests.

Funding

No fundings was obtained for this study.

Acknowledgements

Not Applicable.

Authors’ contributions

XDL designed the study and was major contributors in writing the manuscript. JZ and HDX helped to draft the manuscript. All authors read and approved the final manuscript.

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Translumental Nd:YAG Laser Embolysis for the Treatment of Branch Retinal Artery Occlusion

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