rbof Revista Brasileira de Oftalmologia Rev. bras.oftalmol. 0034-7280 1982-8551 Sociedade Brasileira de Oftalmologia 10.37039/1982.8551.20260041 01813 Case Report Shamrock sign: a novel indicator of myopia in nuclear cataracts Sinal do trevo: um novo indicador de miopia em cataratas nucleares 0000-0001-8756-8114 TeixeiraIvan Corso Substantial contribution to conception and design acquisition of data analysis and interpretation of data drafting of the manuscript critical revision of the manuscript for important intellectual content final approval of the submitted manuscript administrative, technical, or material support supervision research group leadership 1 0000-0003-4441-4304 MoscoviciBernardo Kaplan Substantial contribution to conception and design analysis and interpretation of data critical revision of the manuscript for important intellectual content final approval of the submitted manuscript research group leadership 2 0000-0001-6732-0787 GondimLuís Armando Vitorino Alves de Souza Substantial contribution to conception and design acquisition of data analysis and interpretation of data drafting of the manuscript final approval of the submitted manuscript 3 0009-0008-9210-5809 LucenaJosé Maurilio Tavares de acquisition of data drafting of the manuscript final approval of the submitted manuscript 3 0000-0003-3927-2129 BarretoRoberta Kern Menna acquisition of data drafting of the manuscript final approval of the submitted manuscript 3 0000-0002-9448-8742 CamposMauro Silveira de Queiroz Substantial contribution to conception and design acquisition of data analysis and interpretation of data critical revision of the manuscript for important intellectual content final approval of the submitted manuscript research group leadership 1 2 Hospital de Olhos Paulista São Paulo SP Brazil Hospital de Olhos Paulista, São Paulo, SP, Brazil. Universidade Federal de São Paulo Department of Ophthalmology and Visual Sciences São Paulo SP Brazil Department of Ophthalmology and Visual Sciences, Universidade Federal de São Paulo, São Paulo, SP, Brazil. Santa Casa de Misericórdia de São Paulo Department of Ophthalmology São Paulo SP Brazil Department of Ophthalmology, Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brazil. Bernardo Kaplan Moscovici Rua Cayowaá 854 ap 82 CEP 05018001 +55 11 996140730 bernardokaplan@yahoo.com.br

no conflict of interest.

Ricardo Augusto Paletta Guedes Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil https://orcid.org/0000-0002-9451-738X

 06 05 2026 2026 85 e0041 27 10 2025 05 02 2026 Copyright ©2026 2026 The Author(s) All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License ABSTRACT

This case series presents the shamrock sign, a novel aberrometry pattern characterized by trefoil and coma, as a potential diagnostic marker for nuclear cataracts associated with myopic shift. This study highlights its clinical relevance and contribution to early detection and management. The primary diagnosis was nuclear cataracts inducing myopic shift. All patients underwent phacoemulsification with intraocular lens implantation. Postoperatively, all cases showed marked reductions in higher-order aberrations, including spherical aberration and trefoil, with complete resolution of the shamrock sign. Visual acuity improved significantly, achieving 20/20 in all patients, underscoring the efficacy of surgery in addressing both visual impairment and aberrometry patterns associated with nuclear cataracts. The shamrock sign, identified via aberrometry, may be a reliable diagnostic marker for nuclear cataracts associated with myopia. Its post-surgical resolution underscores its value in guiding clinical decisions and improving diagnostic precision in cataract management.

 RESUMO

Esta série de casos apresenta o sinal do trevo (shamrock sign), um novo padrão em aberrometria caracterizado por trefoil e coma, proposto como possível marcador diagnóstico de catarata nuclear associada a desvio miópico. O estudo destaca sua relevância clínica e contribuição para a detecção precoce e o manejo adequado da condição. O diagnóstico principal foi catarata nuclear induzindo desvio miópico. Todos os pacientes foram submetidos à facoemulsificação com implante de lente intraocular. No pós-operatório, observou-se redução significativa das aberrações de alta ordem – incluindo a aberração esférica e trefoil –, com completa resolução do sinal do trevo. A acuidade visual melhorou expressivamente, atingindo 20/20 em todos os casos, reforçando a eficácia do procedimento, tanto na recuperação visual quanto na normalização dos padrões aberrométricos associados à catarata nuclear. O sinal do trevo, identificado por meio de aberrometria, pode representar um marcador diagnóstico confiável de catarata nuclear associada à miopia. Seu desaparecimento após a cirurgia enfatiza seu valor como ferramenta auxiliar na tomada de decisões clínicas e na maior precisão diagnóstica no manejo da catarata.

 Keywords: Cataract Myopia Aberrometry Lens implantation, intraocular Phacoemulsification Vision disorders Visual acuity Descritores: Catarata Miopia Aberrometria Implante de lente intraocular Facoemulsificação Transtornos da visão Acuidade visual Financial support: no financial support for this work. INTRODUCTION

Cataract remains a predominant cause of blindness worldwide. While myopia is not commonly recognized as a predisposing factor for cataract development, the progression of cataracts, particularly nuclear sclerosis, frequently results in a myopic shift. This myopic shift often precedes cataract formation, especially in patients over the age of 55. However, established clinical signs or objective diagnostic tools to identify nuclear cataracts are limited. (1,2)

The aberrometry OPD Scan III (Nidek, Tokyo, Japan) is a multifunctional device that measures corneal shape, curvature, and wavefront aberrations. Its reproducibility in measuring high-order aberrations (HOA) is well established. The device is widely used in the pre- and postoperative periods of cataract surgery. (3–6)

The literature reports no signs or diagnostic findings associated with cataract-related myopic shift. We examined three patients diagnosed with nuclear cataracts exhibiting a myopic shift tendency. The internal aberrometry images of all patients showed a consistent pattern of a three-leaf clover, designated as the "shamrock sign" (Figure 1). (7–10)

Shamrock sign.

Through detailed case analyses, we aim to emphasize the clinical significance of the shamrock sign as a potential diagnostic marker for nuclear cataracts that induce myopia, even in the very early stages.

Informed consent was obtained from all patients included in this case series, with written authorization for the use of their clinical data and images for research and publication purposes. This study was approved by the Ethics Committee of Hospital de Olhos Paulista, São Paulo, Brazil, under the protocol CAAE number 75264623.0.0000.9867. All procedures adhered to ethical guidelines, ensuring the confidentiality of patient information. Given the nature of this case series, no additional risks were posed to the participants.

 CASE REPORT Case 1

A 60-year-old male presented with worsening visual acuity (VA) in both eyes. The initial refractive assessment revealed a spherical correction of −10.00 D in the right eye (OD) and −5.25 D in the left eye (OS). Nuclear cataracts were graded as 2+ in OD and 1+ in OS. Visual acuity improved postoperatively, and the shamrock sign was significantly reduced (Tables 1–3 and Figure 2).

Summary of cases
Case Age (years) Pre-operativeBCVA (OD/OS) Cataract grade (OD/OS) Pre-operative HOA total μm (OD/OS) Pre-operative HOA internal μm (OD/OS) Pre-operative sphere D (OD/OS) Post-operative BCVA (OD/OS) Post-operative HOA μm (OD/OS) Post-operative HOA internal μm (OD/OS) Shamrock sign pre (OD/OS)
1 60 0.2/0.7 2+/1+ 2.060/0.496 2.462/1.032 -10.00/-5.25 1.0/1.0 0.364/0.239 0.257/0.185 Present/Almost present
2 42 0.5/0.7 2+/1+ 1.304/0.833 1.619/1.024 -8.00/-3.50 1.0/1.0 0.393/0.229 0.317/0.298 Present /Present
3 55 0.4 /0.5 2+/2+ 0.463/0.298 0.495/0.337 -1.50/-1,50 1.0/1.0 0.203/0.152 0.246/0.173 Present/Present

BCVA: best corrected visual acuity; OD: right eye; OS: left eye; HOA: high-order aberrations.

 Internal aberrations in each case
Case Eye Spherical aberration (pre-operative; μm) Coma (pre-operative; μm) Trefoil (pre-operative; μm) Spherical aberration (post-operative; μm) Coma (post-operative; μm) Trefoil (post-operative; μm)
1 OD 2.112 1.007 0.705 0.170 0.083 0.100
1 OS 0.843 0.154 0.503 0.143 0.075 0.065
2 OD 1.316 0.250 0.866 0.175 0.120 0.042
2 OS 0.831 0.205 0.529 0.207 0.154 0.069
3 OD 0.322 0.270 0.181 0.045 0.085 0.141
3 OS 0.249 0.070 0.172 0.079 0.016 0.085 μm

OD: right eye; OS: left eye.

 Aberrometric refraction
Case Eye Pre-operative OPD spherical refraction center Pre-operative OPD spherical refraction total Pos-operative OPD spherical refraction center Pos-operative OPD spherical refraction total
1 OD -10.25 -5.00 (7.90mm) +0.00 -0.25 (5.92 mm)
1 OS -4.75 -4,50 (7.90 mm) +0.25 -0.50 (5.38mm)
2 OD -8.00 -3.00 (6.40mm) +0.25 +0.00 (5.68 mm)
2 OS -3.50 -0.25 (5.98mm) +0.00 -0.25 (5.70 mm)
3 OD -2.00 +0.25 (4.63mm) +0.25 +0.25 (4.06mm)
3 OS -2.25 -0.75 (4.67mm) -0.25 +0.00 (4.28mm)

OD: right eye; OS: left eye.

 (A and B): case 1 pre-operative; (C and D): case 1 post-operative; (E and F): case 2 pre-operative; (G and H): case 2 post-operative; (I and J): case 3 pre-operative; (K and L): case 3 post-operative. Case 2

A 42-year-old female presented with complaints of decreased VA. The initial refractive examination showed a spherical correction of −8.00 D in OD and −3.50 D in OS. Nuclear cataracts were graded as 2+ in OD and 1+ in OS. Postoperative assessments revealed a reduction in HOAs and the shamrock sign, with VA improving to 1.0 in both eyes.

 Case 3

A 55-year-old male patient presented with complaints of blurred vision in both eyes. Preoperative refraction measurements indicated −1.50 diopters of spherical correction in the right eye and −1.50 diopters of spherical correction with an additional −0.50 cylindrical correction in the left eye. Biomicroscopic examination identified a nuclear cataract graded 2+/4+ in both eyes. The aberrometry exam further revealed the presence of the "shamrock sign" in both eyes, with greater prominence in the left eye. The patient was advised to undergo phacoemulsification in both eyes, with implantation of a multifocal intraocular lens. Following surgery, the shamrock sign markedly reduced, and the patient achieved a UCVA of 1.0 in both eyes.

 DISCUSSION

The results presented in this case series underscore the significant impact of nuclear cataracts on HOAs and VA. Cases that underwent surgical intervention showed substantial improvements in VA and reductions in the shamrock sign and internal HOAs. (1–3)

The presence of the shamrock sign appears to be associated with more negative spherical refractive values in the central cornea, as indicated by aberrometric measurements. This observation may be attributed to the specific optical configuration induced by nuclear cataracts, in which the progression of nuclear sclerosis increases lens density, disproportionately affecting the central refraction. This finding is particularly relevant in cases in which the shamrock sign was identified, as these cases consistently exhibited more negative central aberrometric refractive values than those in broader regions. (4–7)

Comparison between central and total aberrometry refraction

Cases 1 and 2 showed a marked difference between the preoperative central and total spherical refraction. For instance, in case 1, the central spherical refraction in the OD was −10.25D, while the total refraction was −5.00D. This discrepancy can be directly linked to the presence of the shamrock sign, which characterizes aberrations that predominantly affect the optical center. (7–10)

Following surgery, the central spherical refraction in the same eye was corrected to +0.00D, and the total refraction to −0.25D, demonstrating an effective correction of the central aberration induced by the nuclear cataract. Similarly, in case 2, the central spherical refraction in the OD was −8.00D, and the total refraction was −3.00D; both were corrected to approximately +0.25D postoperatively, indicating a notable improvement. (1–3)

The central spherical refraction was also more negative than the total refraction, confirming the impact of the shamrock sign on central refraction. This suggests that surgical decisions could be strongly influenced by evaluating the shamrock sign and central refraction, as correcting these central aberrations can lead to substantial improvements in VA. (4–7)

 High-order aberration analysis

Table 1B provides insight into the specific HOAs in each case, with particular emphasis on spherical aberration, coma, and trefoil, both preoperatively and postoperatively. Comparing these aberrations with the grade of nuclear cataracts or the presence of the shamrock sign reveals notable patterns. (1–3)

Spherical aberration and trefoil were particularly elevated in cases with more advanced nuclear cataracts. For instance, in case 1, the preoperative spherical aberration in the right eye was 2.112 μm, significantly higher than in eyes with less advanced cataracts, such as case 3 (0.322 μm in OD). This correlation suggests that higher grades of nuclear cataract are associated with increased spherical aberration, likely due to the progressive lens opacity that distorts central light transmission. Similarly, trefoil was elevated in cases with more pronounced shamrock sign, suggesting that this aberration may be a marker of the optical irregularities associated with this sign. (3–5)

Postoperatively, there was a marked reduction in both spherical aberration and trefoil, particularly in eyes where the shamrock sign was present preoperatively. For example, in case 1, the spherical aberration in OD decreased from 2.112 μm to 0.170 μm postoperatively, and the trefoil decreased from 0.705 μm to 0.100 μm. This significant reduction underscores the efficacy of cataract surgery in addressing the central optical aberrations associated with nuclear cataracts and the shamrock sign. This case series demonstrated that the shamrock sign was consistently present in all three patients with nuclear cataracts and associated myopic shift. In patients who underwent cataract surgery, there was a significant reduction in the shamrock sign postoperatively, accompanied by an improvement in VA to 1.0. The findings suggest that the shamrock sign could be an important diagnostic marker for nuclear cataracts that induce myopia, potentially aiding in early detection and management.

no financial support for this work.

Universidade Federal de São Paulo e Hospital de Olhos Paulista, São Paulo, SP, Brasil.

The authors declare that they have no financial or proprietary interests in any material discussed in this article.

There is nothing to disclose.

 Data availability:

The data that support the findings of this study are not openly available and are available from the corresponding author upon reasonable request. All patients signed informed consent

 REFERENCES NizamiAA GulaniAC Cataract. 2022 Jul 5 StatPearls Treasure Island (FL) StatPearls Publishing 2023 Nizami AA, Gulani AC. Cataract. 2022 Jul 5. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. BrownNA HillAR Cataract: the relation between myopia and cataract morphology Br J Ophthalmol 1987 71 6 405 414 Brown NA, Hill AR. Cataract: the relation between myopia and cataract morphology. Br J Ophthalmol. 1987;71(6):405-14. AsgariS HashemiH JafarzadehpurE MohamadiA RezvanF FotouhiA OPD-Scan III: a repeatability and inter-device agreement study of a multifunctional device in emmetropia, ametropia, and keratoconus Int Ophthalmol 2016 36 5 697 705 Asgari S, Hashemi H, Jafarzadehpur E, Mohamadi A, Rezvan F, Fotouhi A. OPD-Scan III: a repeatability and inter-device agreement study of a multifunctional device in emmetropia, ametropia, and keratoconus. Int Ophthalmol. 2016;36(5):697-705. AsgariS HashemiH OPD scan III accuracy: Topographic and aberrometric indices after accelerated corneal cross-linking J Curr Ophthalmol 2017 30 1 58 62 Asgari S, Hashemi H. OPD scan III accuracy: Topographic and aberrometric indices after accelerated corneal cross-linking. J Curr Ophthalmol. 2017;30(1):58-62. PathakB BoruahBR Improvement in error propagation in the Shack-Hartmann-type zonal wavefront sensors J Opt Soc Am A Opt Image Sci Vis 2017 34 12 2194 2202 Pathak B, Boruah BR. Improvement in error propagation in the Shack-Hartmann-type zonal wavefront sensors. J Opt Soc Am A Opt Image Sci Vis. 2017;34(12):2194-202. Lafetá QueirozRF KniggendorfDV de MedeirosAL HidaWT NakanoCT CarricondoPC Clinical comparison of speculum's influence on intraoperative aberrometry reading Clin Ophthalmol 2019 13 953 958 Lafetá Queiroz RF, Kniggendorf DV, de Medeiros AL, Hida WT, Nakano CT, Carricondo PC, et al. Clinical comparison of speculum's influence on intraoperative aberrometry reading. Clin Ophthalmol. 2019;13:953-8. CruzJC MorenoCB SoaresPV MoscoviciBK Colombo-BarbozaGN Colombo-BarbozaLR Comparison of endothelial cell loss in diabetic patients after conventional phacoemulsification and femtosecond laser-assisted cataract surgery BMC Ophthalmol 2023 23 1 181 181 Cruz JC, Moreno CB, Soares PV, Moscovici BK, Colombo-Barboza GN, Colombo-Barboza LR, et al. Comparison of endothelial cell loss in diabetic patients after conventional phacoemulsification and femtosecond laser-assisted cataract surgery. BMC Ophthalmol. 2023;23(1):181. RiosLC SilvaPG CanamaryAMJúnior RodriguesP RegatieriCV CamposM Centration in refractive surgery Arq Bras Oftalmol 2020 83 1 76 81 Rios LC, Silva PG, Canamary Júnior AM, Rodrigues P, Regatieri CV, Campos M, et al. Centration in refractive surgery. Arq Bras Oftalmol. 2020;83(1):76-81. RodriguesPF MoscoviciBK LamazalesL FreitasMM GomesJA NoséW Measurement of the visual axis through two different methods: quantification and differences for measuring chord μ Arq Bras Oftalmol 2023 S0004-27492023005002305 Rodrigues PF, Moscovici BK, Lamazales L, Freitas MM, Gomes JA, Nosé W, et al. Measurement of the visual axis through two different methods: quantification and differences for measuring chord μ. Arq Bras Oftalmol. 2023:S0004-27492023005002305. MirandaAP SilvaCB MimicaLM MoscoviciBK MalavazziGR HidaRY In vitro antimicrobial analysis of aqueous humor after topical application of moxifloxacin hydrochloride 0.5% J Cataract Refract Surg 2015 41 1 135 139 Miranda AP, Silva CB, Mimica LM, Moscovici BK, Malavazzi GR, Hida RY. In vitro antimicrobial analysis of aqueous humor after topical application of moxifloxacin hydrochloride 0.5%. J Cataract Refract Surg. 2015;41(1):135-9.