Ophthalmic Surgery, Lasers and Imaging Retina

Clinical Science 

Single-Spot Yellow Laser Versus Conventional Green Laser on Panretinal Photocoagulation: Patient Pain Scores and Preferences

Gerardo González-Saldivar, MD; Sergio Rojas-Juárez, MD; Itzel Espinosa-Soto, MD; Jorge Sánchez-Ramos, MD; Noel Jaurieta-Hinojosa, MD; Abel Ramírez-Estudillo, MD

Abstract

BACKGROUND AND OBJECTIVE:

Panretinal photocoagulation (PRP) is the mainstay therapy for proliferative diabetic retinopathy. Pain during and after its application is a complication that affects patients' therapeutic adherence. This study aimed to compare pain perception and patient preference for the 577-nm yellow laser (YL-577) (LIGHTL as 577; LIGHTMED, San Clemente, CA) and the conventional 532-nm green laser (GL-532) (Purepoint Laser; Alcon, Fort Worth, TX) with PRP.

PATIENTS AND METHODS:

A total of 92 patient eyes with proliferative diabetic retinopathy treated with PRP were randomly assigned to receive both GL-532 and YL-577 (184 eyes) — one on each eye, with the order of application randomized, as well. Afterward, verbal rapid answer and visual analogue scale (VAS) scores for pain perception and patient preference were evaluated.

RESULTS:

VAS score was 7 ± 2 for the GL-532 group compared to 5 ± 3 in the YL-577 group (P = .001). Overall, 75% of the patients preferred YL-577 therapy if they were to receive a second PRP session.

CONCLUSION:

The use of YL-577 as an alternative approach for PRP reduces pain perception and is preferred by patients.

[Ophthalmic Surg Lasers Imaging Retina. 2017;48:902–905.]

Abstract

BACKGROUND AND OBJECTIVE:

Panretinal photocoagulation (PRP) is the mainstay therapy for proliferative diabetic retinopathy. Pain during and after its application is a complication that affects patients' therapeutic adherence. This study aimed to compare pain perception and patient preference for the 577-nm yellow laser (YL-577) (LIGHTL as 577; LIGHTMED, San Clemente, CA) and the conventional 532-nm green laser (GL-532) (Purepoint Laser; Alcon, Fort Worth, TX) with PRP.

PATIENTS AND METHODS:

A total of 92 patient eyes with proliferative diabetic retinopathy treated with PRP were randomly assigned to receive both GL-532 and YL-577 (184 eyes) — one on each eye, with the order of application randomized, as well. Afterward, verbal rapid answer and visual analogue scale (VAS) scores for pain perception and patient preference were evaluated.

RESULTS:

VAS score was 7 ± 2 for the GL-532 group compared to 5 ± 3 in the YL-577 group (P = .001). Overall, 75% of the patients preferred YL-577 therapy if they were to receive a second PRP session.

CONCLUSION:

The use of YL-577 as an alternative approach for PRP reduces pain perception and is preferred by patients.

[Ophthalmic Surg Lasers Imaging Retina. 2017;48:902–905.]

Introduction

Proliferative diabetic retinopathy remains a leading cause of visual impairment in economically active populations in developing, as well as developed, countries. It results in 12,000 to 24,000 new cases of blindness each year in the United States.1,2 Diabetic visual impairment might be prevented by two main strategies: early diabetic retinopathy diagnosis and panretinal photocoagulation (PRP) therapy.1 Many multinational trials have shown the benefits of PRP in high-risk proliferative diabetic retinopathy (PDR), where a reduction of severe visual loss in up to 60% of cases has been reported.1,3 However, pain is its most prevalent short-term complication, leading to a loss of compliance to subsequent laser sessions in the medium and long term.4 Clinical trials with oral nonsteroidal anti-inflammatory drugs, intramuscular anesthetic medications, or peribulbar anesthesia have been carried out with inconsistent results; in addition, these procedures are not free from complications.5,6

In the last two decades, new technologies, such as 577 nm or 810 nm wavelengths, which have a major affinity for retinal pigment epithelium, and different forms of application with less fluence or pattern scan lasers for PRP have been developed.4,7,8 They have been successful, with less pain, complications, and time involved.7,8 Yellow laser 577-nm (YL-577) (LIGHTL as 577; LIGHTMED, San Clemente, CA), with peak absorption on oxyhemoglobin and good absorption by melanin, has been found to produce retinal laser burns with lower power levels (26% less) and better penetration through cataracts compared with previous laser technologies.9 This feature makes it reasonable to speculate that there will be less pain and improvement in patient comfort and compliance to future PRP sessions when compared to conventional 532-nm green laser (GL-532) (Purepoint Laser; Alcon, Fort Worth, TX). There are some studies comparing pain prevalence and intensity with new technologies for PRP;4,8,10,11 however, there are no studies comparing YL-577 and GL-532 with local pain assessment as a primary endpoint.

We conducted a prospective, double-blind, randomized, cross-sectional, self-controlled, interventional study to compare YL-577 and GL-532 for PRP in PDR. Pain prevalence and intensity were the primary endpoints to evaluate YL-577 as an alternative approach for PRP. Demographic characteristics, laser parameters, and patients' preference after a PRP session were secondary endpoints.

Patients and Methods

Institutional review board approval as well as written informed consent from all participants were obtained. The study adhered to the Helsinki Declaration. Ninety-three consecutive cases of men and women between 30 years of age and 70 years of age with a diagnosis of high-risk PDR understood as optic disc neovascularization greater than one-third disc area, neovascularization elsewhere greater than one-quarter disc area, or any neovascularization with pre-retinal or vitreous hemorrhage within both eyes, naïve to PRP laser therapy were invited to participate in the study. Participants were enrolled between June and October 2016. None declined to participate in the trial. Exclusion criteria included patients with previous diagnoses of any type of glaucoma, significant media opacities, a history of ocular surgery within 6 months prior to enrollment, and tractional or combined retinal detachment. A total of 184 eyes were evaluated in the study protocol.

Study Protocol

After clinical evaluation and routine procedures for diabetic patients with visual impairment and establishment of a diagnosis of high-risk PDR, participants were randomized in a masked fashion to receive YL-577 and GL-532, one for each eye. All patients were treated by one of two experienced surgeons and underwent a single PRP session with topical anesthesia 5 min before the procedure. Laser was applied on repeat mode with an interval between shots of 100 ms. Spot size (400 μm) and pulse duration (100 ms) were used to obtain a white-grayish spot (Grade 2 to 3 ETDRS) on the retina in both eyes on the same day. In order to objectively compare pain score responses, PRP was applied in single-spot mode and within similar retinal areas, avoiding meridians 3 and 9 because of the ciliary nerves. The total amount of spots was equivalent for both eyes (700 spots).12 There was a record for the variety of laser assigned to the right or left eye and the first laser modality applied. The intervention was blinded to the participant as well as to the senior resident applying the survey. The surgeons who applied the PRP sessions did not have access to survey results. Assessment of the pain score was applied 5 minutes after the end of each therapy; preference was assessed at the end of study participation.

Patients and Methods

PRP therapy was carried out by YL-577 and by GL-532. The pain score was assessed at the end of each application and included two methods: 1) a rapid verbal answer (RVA) describing pain as “none,” “mild,” “moderate,” or “severe,” and 2) a visual analog scale (VAS) for pain indicating the score from “0,” representing no pain, to “10,” representing the most severe pain they have experienced. In order to obtain patient preference, at the end of both procedures and questionnaires, patients were asked to express which type of laser they would prefer to receive if they underwent another PRP session.

Statistics

The statistical analyses were done using SPSS Statistics 20.0 (IBM, Armonk, NY). We conducted a descriptive statistical analysis for quantitative variables, measures of central tendency, and dispersion. In the case of qualitative variables, frequencies and percentages were obtained and data were compared using Pearson's Chi-square test or Fisher's exact test for 2 × 2 tables. In quantitative comparative variables, the one sample Kolmogorov-Smirnov test was used to test the distribution of the data and depending on its result, we used an unpaired Student's t or the Mann-Whitney test as well as a paired Student's t or Wilcoxon test when necessary. A P value of less than .05 was considered statistically significant.

Results

A total of 184 eyes from 92 participants (42 women and 50 men) with Type 2 diabetes diagnosed with high-risk PDR were treated with PRP between June and October 2016. The mean age of the whole study group was 55.86 years (range: 38 years to 70 years), and 47 of the 92 participants received YL-577 as the first applied laser during their PRP session.

A comparison of laser parameters between the two groups of PRP is shown in Table 1. All patients reported some degree of pain after receiving PRP with GL-532. In contrast, only 81.5% of patients reported pain after receiving YL-577 (P = .002). Severe pain was reported in 31 out of 92 patients with GL-532 PRP, in contrast to 14 out of 92 with YL-577 (P = .0036). When pain perception was assessed by VAS, YL-577 participants reported statistically significantly less pain than the GL-532 group. The mean VAS score was 7 ± 2 for the GL-532 group compared to 5 ± 3 in the YL-577 group (P = .001).

Study Population Compared by First Appliance and Laser Characteristics

Table 1:

Study Population Compared by First Appliance and Laser Characteristics

Immediately after the application of both types of laser therapy, preference for one of these modalities was evaluated. As an overall group, 75% of the participants preferred YL-577 in comparison to 25% of the participants selecting GL-532 (P = .002) (Table 2).

Pain Perception and Patient Preference

Table 2:

Pain Perception and Patient Preference

In order to achieve a white-grayish spot (Grade 2–3 ETDRS) on the retina, GL-532 PRP required a mean power of 326 mW ± 97 mW, whereas YL-577 needed only 318 mW ± 116 mW. There was a trend for a low power in YL-577; this difference, however, was not statistically significant (P = .615).

Discussion

The advent of photocoagulation in 1967 was a vital step in the treatment of diabetic retinopathy. Although some studies have demonstrated that anti-vascular endothelial growth factor therapy reduces progression in diabetic retinopathy,2 PRP continues to be one of the main therapeutic modalities. The search for better visual outcomes and minimization of side effects has resulted in the development of new improved photocoagulation technological systems and optimization of parameters such as wavelengths, energy levels, and pulse duration. Despite these technological advances, PRP is still an unpleasant experience for most patients4 and it has been recognized that up to 100% of patients experience pain during PRP.10 For this reason, multiple alternatives have been suggested to try to reduce the perception of pain, such as the use of topical and oral analgesics or even periocular anesthetics with the risks that this implies5 The response to pain among patients may vary depending on factors such as gender, threshold of pain, and history of previous laser treatment.10 None of the patients included in our study had a previous history of laser treatment. Also, there was no statistical difference either in gender or age. Additionally, randomization of eye allocation and first type of laser applied provided a more non-biased assessment of pain. Our study reported at least some level of pain in 100% of patients treated with GL-532, whereas only 81.5% of patients in the YL-577 group mentioned it. In this latter group, 18.5% absolutely denied it. It is likely that this finding will improve further patient adherence to future laser sessions with YL-577.

Despite several studies that have been carried out comparing different application techniques, different fluence parameters, or different wavelengths,4,8,10,11 there are no studies comparing pain response to YL-577 with GL-532. Our outcomes show that in a single-session (700 spots), single-spot (400 nm), and constant exposure time (100 ms), making wavelength and power the only variable, YL-577 was significantly less painful and more comfortable for patients with PDR compared to GL-532. The difference in pain perception between patients in the conventional green laser and YL-577 groups was statistically significant for both pain scales. Patient preference has been shown to improve therapeutic adherence in other medical conditions as well as in diabetic retinopathy.13 Further evaluation of this specific issue should be carried out. Discussion of this topic with the patient could delay future laser applications, particularly in patients without adherence to their overall diabetic management.

Patient preference is a variable that has also never been studied in PRP application. In our study, only 25% of the patients preferred GL-532, whereas the other 75% preferred a second PRP session with the YL-577. A less painful application session was the main reason to improve preference for this technology. Surely, preference to YL-577 and a lower degree of pain during laser sessions will lead to improved adherence and, likely, the future of visual acuity in a patient with diabetes.

Conclusion

PRP is still a therapeutic modality that is associated with an unpleasant pain experience. Nevertheless, it continues to be the gold standard in the management of PDR. The use of YL-577 as an alternative approach preferred by patients who have undergone PRP will allow opportune therapy and patient adherence to treatment, which might be reflected as a better reduction in PDR progression.

References

  1. No authors listed. Fundus photographic risk factors for progression of diabetic retinopathy. ETDRS report number 12. Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. 1991;98(5 Suppl):823–833. doi:10.1016/S0161-6420(13)38014-2 [CrossRef]
  2. Gross JG, Glassman AR, Jampol LM, Writing Committee for the Diabetic Retinopathy Clinical Research Network et al. Panretinal photocoagulation vs intravitreous ranibizumab for proliferatice diabetic retinopathy: A randomized clinical trial. JAMA. 2015;314(20):2137–2146. doi:10.1001/jama.2015.15217 [CrossRef]
  3. Flynn HW Jr, Chew EY, Simons BD, Barton FB, Remaley NA, Ferris FL 3rd, . Pars plana vitrectomy in the Early Treatment Diabetic Retinopathy Study. ETDRS report number 17. The Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. 1992;99(9):1351–1357. doi:10.1016/S0161-6420(92)31779-8 [CrossRef]
  4. Alvarez-Verduzco O, Garcia-Aguirre G, Lopez-Ramos Mde L, Vera-Rodriguez S, Guerrero-Naranjo JL, Morales-Canton V. Reduction of fluence to decrease pain during panretinal photocoagulation in diabetic patients. Opthalmic Surg Lasers Imaging. 2010;41(4):432–436. doi:10.3928/15428877-20100525-02 [CrossRef]
  5. Wu WC, Hsu KH, Chen TL, et al. Interventions for relieving pain associated with panretinal photocoagulation: A prospective randomized trial. Eye (Lond). 2006;20(6):712–719. doi:10.1038/sj.eye.6701989 [CrossRef]
  6. Nascimento VP, Primiano HP Jr, Maia OO Jr, Pelayes D, Takahashi WY. Analgesic effect of etoricoxib (Arcoxia) 120 mg during retinal laser photocoagulation. Eur J Ophthalmol. 2012;22(3):388–392. doi:10.5301/ejo.5000028 [CrossRef]
  7. Inan UU, Polat O, Inan S, Yigit S, Bayasal Z. Comparison of pain scores between patients undergoing panretinal photocoagulation using navigated or pattern scan laser systems. Arq Bras Oftalmol. 2016;79(1):15–18. doi:10.5935/0004-2749.20160006 [CrossRef]
  8. Muqit MM, Marcellino GR, Gray JC, et al. Pain responses of Pascal 20 ms multi-spot and 100 ms single-spot panretinal photocoagulation: Manchester Pascal Study, MAPASS report 2. Br J Ophthalmol. 2010;94(11):1493–1498. doi:10.1136/bjo.2009.176677 [CrossRef]
  9. Sramek CK, Leung LS, Paulus YM, Palanker DV. Therepautic window of retinal photocoagulation with green (532-nm) and yellow (577-nm) lasers. Ophthalmic Surg Lasers Imaging. 2012;43(4):341–347. doi:10.3928/15428877-20120426-05 [CrossRef]
  10. Mirshahi A, Lashay A, Roozbahani M, et al. Pain score of patients undergoing single spot, short pulse laser versus conventional laser for diabetic retinopathy. Graefes Arch Clin Exp Ophthalmol. 2013;251(4):1103–1107. doi:10.1007/s00417-012-2167-5 [CrossRef]
  11. Seymenoğlu G, Kayıkçıoğlu O, Başer E, İlker SS. Comparison of pain response of patients undergoing panretinal photocoagulation for proliferative diabetic retinopathy: 532 nm standard laser vs. multispot pattern scan laser. Turk J Ophthalmol. 2013;43:221–224.
  12. No authors listed. Early photocoagulation for diabetic retinopathy. ETDRS report number 9. Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. 1991;98(5 Suppl):766–785.
  13. Wirostko B, Beusterien K, Grinspan J, et al. Patient preferences in the treatment of diabetic retinopathy. Patient Prefer Adherence. 2011;5:229–327.

Study Population Compared by First Appliance and Laser Characteristics

GL-532 (n = 47)YL-577 (n = 45)P Value
Men, n (%)26 (54.3)24 (54.3).848
Women, n (%)21 (45.7)21 (45.7)
Age, Mean ± SD (Years)55.29 (±9.31)56.15 (±7.48).629
Spot, Mean ± SD (μm)399 (±10)399 (±10)1
Interval, Mean ± SD (sec)0.1 (±0)0.1 (±0).157
Exposure, Mean ± SD (sec)0.1 (±0)0.1 (±0)1
Power, Mean ± SD (mW)326 (±97)318 (±116).419
Spots, Mean ± SD700 (±0)700 (±0)1
Affluence, Mean ± SD26.07 (±7.59)25.48 (±9.24).64
Total Affluence, Mean ± SD18,251.88 (±5,314.39)17,842.84 (±6,471.14).64

Pain Perception and Patient Preference

GL-532 (n = 47)YL-577 (n = 45)P Value

Pain Perception, n (%)
  12 (2.2)17 (18.5).0002
  220 (21.7)40 (43.5).0016
  339 (42.4)21 (22.8).0046
  431 (33.7)14 (15.2).0036

VAS, Mean ± SD7 (± 2)5 (± 3)< .001

No Pain, n (%)0 (0)17 (18.5).002

Pain, n (%)92 (100)75 (81.5)

Laser Preference, n (%)23 (25)69 (75)

Laser Preference When First Applied, n (%)10 (43.5)32 (46.4).399
Authors

From Fundación Hospital Nuestra Señora de La Luz, IAP, Retina Department, Mexico City.

The authors report no relevant financial disclosures.

Address correspondence to Abel Ramírez-Estudillo, MD, Fundación Hospital Nuestra Señora de La Luz, IAP, Departamento de Retina, Calle Ezequiel Montes # 135, Deleg. Cuauhtémoc, Colonia Tabacalera, Ciudad de México, México C.P. 06030; email: ramirezestudillo@gmail.com.

Received: March 04, 2017
Accepted: June 02, 2017

10.3928/23258160-20171030-05

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