Occlusion Break Surge and Anterior Chamber Stability in the Intraocular Environment of Modern Phacoemulsification: A Narrative Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors attempted to investigate current experimental and clinical evidence on the pathophysiology, quantification, and technological control of surge, framing it as a model of environmentally driven intraoperative stress. However, several issues require further clarification and discussion in the manuscript.

First, the authors needed to include the PRISMA flow diagram of search procedure for narrative review [1].

The authors needed to add the manufacturer’s information for several products including the Active Sentry system, Active Fluidics, Centruion Vision System, Adaptive Fluidics, and so on in the whole manuscript.  

References

1. Coupe N, Peters S, Rhodes S, Cotterill S. The effect of commitment-making on weight loss and behaviour change in adults with obesity/overweight; a systematic review. BMC Public Health 2019;19(1):816.

Author Response

Comment 1. The authors attempted to investigate current experimental and clinical evidence on the pathophysiology, quantification, and technological control of surge, framing it as a model of environmentally driven intraoperative stress. However, several issues require further clarification and discussion in the manuscript.

First, the authors needed to include the PRISMA flow diagram of search procedure for narrative review [1].

Response:

We appreciate the reviewer’s emphasis on transparency in the literature search process. This manuscript was designed and conducted as a narrative review rather than as a systematic review or meta-analysis; therefore, a PRISMA flow diagram is not required for the intended study design.

Nevertheless, in response to this comment, we strengthened the Methods section to improve reproducibility within a narrative framework. We now report: (i) the databases searched, (ii) a representative Boolean search strategy, (iii) the date of the last search, and (iv) a quantitative screening and inclusion funnel with record counts. These revisions provide transparent documentation of how the evidence base was assembled while remaining consistent with a narrative synthesis approach.

Comment 2. The authors needed to add the manufacturer’s information for several products including the Active Sentry system, Active Fluidics, Centruion Vision System, Adaptive Fluidics, and so on in the whole manuscript.

References

1. Coupe N, Peters S, Rhodes S, Cotterill S. The effect of commitment-making on weight loss and behaviour change in adults with obesity/overweight; a systematic review. BMC Public Health 2019;19(1):816.

Response:

We thank the reviewer for highlighting the importance of clearly documenting manufacturer sources. In the revised manuscript, we explicitly cite manufacturer technical documentation only where peer-reviewed data are limited, particularly for next-generation platforms.

Specifically, official technical sources are now cited for Unity VCS (Alcon) and Quatera 700 with Centrally Controlled Fluidics (ZEISS) (refs. [33] and [34]), and these are clearly labeled as manufacturer technical information in both the main text and Table 3.

For established technologies such as Active Fluidics, Active Sentry, and the Centurion Vision System, we primarily rely on peer-reviewed bench and clinical studies (e.g., refs. [12–14, 20, 30–32]). We also performed a full cross-check of all platform-specific statements and their corresponding citations to ensure accurate and transparent source attribution throughout the manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

The scope framing feels inflated and a bit disconnected from the actual technical contribution. The opening sentence, “In an era in which the impact of environmental and lifestyle factors on human health is increasingly recognised”, sets up a broad “environment” theme. Still, most of the review is fluidics engineering and anterior chamber stability. That rhetorical bridge is unnecessary and risks appearing trend-following rather than scholarship. The introduction would be more substantial if it moved directly from cataract surgery fluidics to surgery, without the “environment/lifestyle” preamble.

The “narrative review” methods section is described as structured, but it is not reproducible as written. The authors say: “Electronic searches were performed in PubMed, Embase, and Scopus from January 2010 to April 2025” and list example terms, but they do not provide an actual search string, date of last search, number of hits, number included, or even approximate yields. Even for a narrative review, a reader needs at least minimal transparency (e.g., counts and the broad inclusion funnel) to judge whether the synthesis is selective.

There is a major chronological inconsistency that undermines trust in the evidence base. The methods claim coverage “January 2010 to April 2025”, yet the references include multiple papers dated after April 2025 (e.g., “Clin Ophthalmol. 2025 Apr 23” [20], “2025 Jun 12” [24], “2025 Jul 1” [23], “2025 Aug” [21], “2025 Sep 30” [26], “2025 Oct” [28]). Either the search window is wrong, or the inclusion statement is incorrect, or the review has been updated without updating the methods. This is not a minor detail; it affects how readers interpret “current” evidence.

Related to that, the manuscript sometimes cites outside its own stated date limits without explanation. For instance, Table 1 lists “Thorne 2018. [4]” and the reference list contains a key 2009 study (“J Cataract Refract Surg. 2009 Aug” [3]) and even 2005/2007 studies ([19], [18]). Those older studies are arguably essential, but then the eligibility statement “published between 2010 and 2025” is simply not true as written. If the authors want foundational pre-2010 studies (reasonable), they should explicitly allow them rather than quietly including them.

Several in-text numeric conversions are presented as precise, but the denominator is not defined, and the quantities are mixed. For example, “volumetric loss … 7% to 66% of the total aqueous humor volume in a phakic eye” is not a clean comparison unless the authors specify what they are calling “total aqueous humour volume” and what value they assume. Elsewhere, they convert surge volume to “% of anterior chamber volume” (e.g., “30–103 µL, corresponding to 12–41% of anterior chamber volume”). “Total aqueous humour volume” and “anterior chamber volume” are not the same thing; mixing them makes the percentage claims look more dramatic than they may be, and it prevents cross-platform comparisons unless a single consistent reference volume is stated.

The numeric reporting in Table 3 is particularly messy and sometimes internally inconsistent. One row has a stray character: “67–163 µL (27–65% of AC volume) [5].0” (that trailing “0” looks like an editing error). Several rows say “Not specifically reported” for surge duration while the text elsewhere makes duration comparisons; the authors should not imply temporal superiority (“shorter”, “rapid”) without consistently tabulating actual durations and settings. There is also an “estimated” duration for Legion (“≈70–90 ms (estimated)”) with no citation, which reads like speculation rather than review.

Some citations appear mismatched to the claims being made, which is a numerical red flag because it prevents verification of the quoted values. For example, Table 1 lists “Dyk & Miller 2020 [6]”, but reference [6] is “2018 Feb;44(2):231-236”. That is not a harmless typo; it suggests the table was compiled from memory or secondary sources and not carefully checked. Similarly, Table 3 attributes Quatera 700 surge duration to “≈221–471 ms [3]”, but reference [3] is a 2009 comparison of “3 new phacoemulsification systems” and is very unlikely to contain 2021 Quatera 700 data. If the authors are going to present quantitative ranges, the linkage between the number and the source must be exact.

The manuscript’s section numbering is also inconsistent in a way that makes it hard to cite or navigate. It has “6.4 Quatera 700”, “6.5 Unity VCS”, then later “6.5. Dedicated Analysis: Quatera 700 and Unity VCS”. That duplicate numbering is a structural error and will confuse review and production. It also raises suspicion that sections were inserted late without a global consistency check.

The equations in section 8.2 have clear dimensional and sign-convention problems that need correction (this is one of the biggest numerical issues). The authors write: “U₀ = ½ · C_sys * (Vac_set)²” and then define “C_sys is the system compliance [mmHg⋅µL]”. If compliance is meant in the usual sense (volume change per pressure change), it should be something like µL/mmHg, not mmHg·µL. As written, the unit propagation does not make sense (mmHg·µL × mmHg² = mmHg³·µL). Either the symbol is not compliant, or the units are wrong, or the energy expression is not derived correctly. Likewise, they state “Q_as = (IOP + Vac_pass) * R” followed by “Vac_pass = (R * Q_as) − IOP”. These relationships invert the usual resistance form (Q = ΔP/R) unless R is defined as a conductance. Yet, later they describe “R is the flow resistance” and give “R … set at approximately 5 … closer to 7” without units. If R is dimensionless, the equation cannot be dimensionally correct; if it has units, those need to be stated. The manuscript should either remove these equations or re-derive them with explicit sign conventions (vacuum is negative pressure) and correct units.

Even where numbers are plausible, the comparison logic is sometimes overstated, given the evidence type. For example, “Preliminary data indicate aqueous volume losses consistently below 60 µL” and “Unity VCS shows early evidence of the lowest aqueous volume losses” are phrased like settled facts. However, the same paragraph admits “full peer-reviewed validation is still pending” and the references include manufacturer technical overviews (“Alcon Vision LLC… Technical Overview. 2025”). A more defensible wording would clearly separate peer-reviewed bench/clinical outcomes from manufacturer claims, and avoid superlatives (“lowest”) unless the review demonstrates a like-for-like comparison under matched settings.

There are also subtle inconsistencies in the way percentage ranges are presented. For Centurion + Active Sentry, Table 3 reports “≤74.7 µL; <20–30% aqueous loss”, while earlier text says “aqueous losses consistently below 30%”. “<20–30%” is not a coherent inequality; it reads like “between <20 and 30” or “<20 to 30”, which are different statements. If the authors are converting µL to %, they need to state the assumed chamber volume used for each conversion and ensure the inequality language is mathematically consistent.

The conflict-of-interest presentation needs tightening because it intersects with device performance claims. The manuscript says: “The authors thank Gaston Laphitz… (Surgical Franchise, Alcon LATAM), for technical support and valuable information.” Immediately after, it declares: “The authors declare no conflicts of interest.” That combination will raise eyebrows because the paper contains multiple comparative statements favourable to Alcon platforms (e.g., “Centurion… currently represents the most extensively validated system”). Even if there is no financial conflict, the authors should explicitly clarify what “technical support” involves and whether any data or interpretations were influenced by manufacturer input.

Finally, the end matter includes template text that should never appear in a submitted manuscript. The “Author Contributions” section begins: “For research articles with multiple authors, a short paragraph outlining each author's individual contributions must be provided… Please turn to the CRediT taxonomy…” That is an instruction to authors from the journal template, not content. Its presence strongly suggests the submission has not been properly edited and will irritate reviewers and editors.

Author Response

Rev2#

COMMENT. The scope framing feels inflated and a bit disconnected from the actual technical contribution. The opening sentence, “In an era in which the impact of environmental and lifestyle factors on human health is increasingly recognised”, sets up a broad “environment” theme. Still, most of the review is fluidics engineering and anterior chamber stability. That rhetorical bridge is unnecessary and risks appearing trend-following rather than scholarship. The introduction would be more substantial if it moved directly from cataract surgery fluidics to surgery, without the “environment/lifestyle” preamble.

Response 1: We agree that the introduction should more directly reflect the technical focus of the review. Accordingly, the opening paragraph has been revised to remove the broader environmental and lifestyle framing and to begin instead with the intraoperative intraocular environment during phacoemulsification, emphasizing fluidics, pressure regulation, and anterior chamber stability.

In parallel, the reference list supporting this section was updated: five of the original references cited in the introduction were replaced with more directly relevant engineering- and surgery-focused literature to better align the framing with the technical scope of the manuscript.

COMMENT. The “narrative review” methods section is described as structured, but it is not reproducible as written. The authors say: “Electronic searches were performed in PubMed, Embase, and Scopus from January 2010 to April 2025” and list example terms, but they do not provide an actual search string, date of last search, number of hits, number included, or even approximate yields. Even for a narrative review, a reader needs at least minimal transparency (e.g., counts and the broad inclusion funnel) to judge whether the synthesis is selective.

Response 2: We revised the Methods section to improve transparency and reproducibility while maintaining a narrative design. The revised version now reports the date of the last search (15 December 2025), provides a representative PubMed Boolean query (with equivalent controlled vocabulary adapted for Embase and Scopus), and includes a quantitative selection funnel (records retrieved, duplicates removed, full texts assessed, and final included references).

An overview table summarizing the main evidence domains incorporated into the narrative synthesis has also been retained. Given the heterogeneity of bench, modeling, and clinical study designs, no formal risk-of-bias assessment or PRISMA-style synthesis was performed.

COMMENT. There is a major chronological inconsistency that undermines trust in the evidence base. The methods claim coverage “January 2010 to April 2025”, yet the references include multiple papers dated after April 2025 (e.g., “Clin Ophthalmol. 2025 Apr 23” [20], “2025 Jun 12” [24], “2025 Jul 1” [23], “2025 Aug” [21], “2025 Sep 30” [26], “2025 Oct” [28]). Either the search window is wrong, or the inclusion statement is incorrect, or the review has been updated without updating the methods. This is not a minor detail; it affects how readers interpret “current” evidence.

Response 3: We acknowledge this inconsistency. The initially stated search window (January 2010 to April 2025) corresponded to an earlier draft of the manuscript, which was subsequently updated prior to submission to incorporate recently published experimental and clinical studies relevant to contemporary phacoemulsification fluidics and surge mitigation. In the revised version, we have harmonized the temporal scope by extending the search period to January 2010–December 2025 and explicitly stating the date of the last search (15 December 2025). All references published after April 2025 are now fully consistent with the revised inclusion criteria and documented search window.

COMMENT. Related to that, the manuscript sometimes cites outside its own stated date limits without explanation. For instance, Table 1 lists “Thorne 2018. [4]” and the reference list contains a key 2009 study (“J Cataract Refract Surg. 2009 Aug” [3]) and even 2005/2007 studies ([19], [18]). Those older studies are arguably essential, but then the eligibility statement “published between 2010 and 2025” is simply not true as written. If the authors want foundational pre-2010 studies (reasonable), they should explicitly allow them rather than quietly including them.

Response 4: We agree that the original wording was too restrictive. Section 2.3 has been revised to clarify that, while the review primarily focused on literature published between 2010 and 2025, selected seminal pre-2010 studies were intentionally included when foundational for surge mechanisms, measurement methodologies, or the historical evolution of phacoemulsification fluidics. This makes the chronological eligibility criteria explicit and consistent with the final reference list.

COMMENT. Several in-text numeric conversions are presented as precise, but the denominator is not defined, and the quantities are mixed. For example, “volumetric loss … 7% to 66% of the total aqueous humor volume in a phakic eye” is not a clean comparison unless the authors specify what they are calling “total aqueous humour volume” and what value they assume. Elsewhere, they convert surge volume to “% of anterior chamber volume” (e.g., “30–103 µL, corresponding to 12–41% of anterior chamber volume”). “Total aqueous humour volume” and “anterior chamber volume” are not the same thing; mixing them makes the percentage claims look more dramatic than they may be, and it prevents cross-platform comparisons unless a single consistent reference volume is stated.

Response 5: We standardized all relative surge metrics to a single, anatomically defined reference volume: the anterior chamber volume (ACV). The term “total aqueous humor volume” has been removed throughout the manuscript. The reference ACV is now explicitly defined as approximately 200–300 µL (reference value ~250 µL) for a phakic adult eye, and this normalization is stated in the main text and the Table 3 footnote. A methodological note clarifies that ACV varies with axial length and anterior segment anatomy and that percentage values should be interpreted as normalized estimates rather than patient-specific measurements.

COMMENT. The numeric reporting in Table 3 is particularly messy and sometimes internally inconsistent. One row has a stray character: “67–163 µL (27–65% of AC volume) [5].0” (that trailing “0” looks like an editing error). Several rows say “Not specifically reported” for surge duration while the text elsewhere makes duration comparisons; the authors should not imply temporal superiority (“shorter”, “rapid”) without consistently tabulating actual durations and settings. There is also an “estimated” duration for Legion (“≈70–90 ms (estimated)”) with no citation, which reads like speculation rather than review

Response 6: We performed a comprehensive revision of Table 3 and the surrounding text. Typographical errors were corrected, and all volumetric-to-percentage conversions were normalized to a single stated ACV reference (~250 µL), now disclosed in the table footnote.

Quantitative surge duration values (ms) are now reported only when explicitly available from bench or experimental sources. Where the literature provides only descriptive assessments, entries are labeled as qualitative (e.g., “variable” or “shorter”). Unsourced estimated values were removed or replaced with data directly supported by cited sources.

A clarifying paragraph preceding Table 3 was also added to inform readers of the heterogeneity in duration reporting and to discourage overinterpretation of comparative claims.

COMMENT. Some citations appear mismatched to the claims being made, which is a numerical red flag because it prevents verification of the quoted values. For example, Table 1 lists “Dyk & Miller 2020 [6]”, but reference [6] is “2018 Feb;44(2):231-236”. That is not a harmless typo; it suggests the table was compiled from memory or secondary sources and not carefully checked. Similarly, Table 3 attributes Quatera 700 surge duration to “≈221–471 ms [3]”, but reference [3] is a 2009 comparison of “3 new phacoemulsification systems” and is very unlikely to contain 2021 Quatera 700 data. If the authors are going to present quantitative ranges, the linkage between the number and the source must be exact.

Response 7: We conducted a full, line-by-line audit of all in-text citations and table entries against the final reference list. The inconsistencies identified were traced to residual reference numbering from an earlier manuscript version.

All tables have been rebuilt with direct verification of each quantitative and qualitative claim against its primary source. Reference numbers have been updated accordingly, and manufacturer technical documentation is now explicitly identified where contemporary platform data are reported. A final consistency check ensures that all numeric ranges and performance metrics are now traceable to their corresponding references.

COMMENT. The manuscript’s section numbering is also inconsistent in a way that makes it hard to cite or navigate. It has “6.4 Quatera 700”, “6.5 Unity VCS”, then later “6.5. Dedicated Analysis: Quatera 700 and Unity VCS”. That duplicate numbering is a structural error and will confuse review and production. It also raises suspicion that sections were inserted late without a global consistency check.

Response 8: We performed a complete structural audit of section and subsection numbering across the manuscript. The comparative platform analysis has been consolidated into a single, consistently numbered subsection, and all subsequent sections have been renumbered accordingly. All in-text cross-references to sections, tables, and figures were verified for consistency with the revised structure.

COMMENT. The equations in section 8.2 have clear dimensional and sign-convention problems that need correction (this is one of the biggest numerical issues). The authors write: “U₀ = ½ · C_sys * (Vac_set)²” and then define “C_sys is the system compliance [mmHg⋅µL]”. If compliance is meant in the usual sense (volume change per pressure change), it should be something like µL/mmHg, not mmHg·µL. As written, the unit propagation does not make sense (mmHg·µL × mmHg² = mmHg³·µL). Either the symbol is not compliant, or the units are wrong, or the energy expression is not derived correctly. Likewise, they state “Q_as = (IOP + Vac_pass) * R” followed by “Vac_pass = (R * Q_as) − IOP”. These relationships invert the usual resistance form (Q = ΔP/R) unless R is defined as a conductance. Yet, later they describe “R is the flow resistance” and give “R … set at approximately 5 … closer to 7” without units. If R is dimensionless, the equation cannot be dimensionally correct; if it has units, those need to be stated. The manuscript should either remove these equations or re-derive them with explicit sign conventions (vacuum is negative pressure) and correct units.

Response 9: Following your recommendation and internal discussion, we concluded that retaining explicit equations was not essential to the primary objective of this narrative review.  Accordingly, Section 8.2 has been rewritten in a concept-driven, system-level framework that preserves the underlying physical principles (system compliance, vacuum buildup, resistive pressure losses, and platform-specific control mechanisms) while eliminating potential ambiguities in unit propagation and sign conventions.

The revised section emphasizes the relationship between compliance, vacuum accumulation, and surge magnitude, the distinction between true occlusion-related vacuum and baseline resistive pressure losses, and the role of modern pump monitoring and venting strategies in facilitating controlled pressure recovery.

COMMENT. Even where numbers are plausible, the comparison logic is sometimes overstated, given the evidence type. For example, “Preliminary data indicate aqueous volume losses consistently below 60 µL” and “Unity VCS shows early evidence of the lowest aqueous volume losses” are phrased like settled facts. However, the same paragraph admits “full peer-reviewed validation is still pending” and the references include manufacturer technical overviews (“Alcon Vision LLC… Technical Overview. 2025”). A more defensible wording would clearly separate peer-reviewed bench/clinical outcomes from manufacturer claims, and avoid superlatives (“lowest”) unless the review demonstrates a like-for-like comparison under matched settings.

Response 10: We revised the wording throughout the manuscript to clearly distinguish peer-reviewed bench and clinical evidence from manufacturer technical documentation. Statements derived from non–peer-reviewed sources are now explicitly labeled as preliminary or hypothesis-generating, and superlative language has been removed unless supported by like-for-like comparisons under matched experimental conditions. The same distinction is reflected in Table 3.

 

COMMENT. There are also subtle inconsistencies in the way percentage ranges are presented. For Centurion + Active Sentry, Table 3 reports “≤74.7 µL; <20–30% aqueous loss”, while earlier text says “aqueous losses consistently below 30%”. “<20–30%” is not a coherent inequality; it reads like “between <20 and 30” or “<20 to 30”, which are different statements. If the authors are converting µL to %, they need to state the assumed chamber volume used for each conversion and ensure the inequality language is mathematically consistent.

Response 11: All volumetric-to-percentage conversions have been harmonized to a single stated ACV reference (~250 µL, phakic adult eye), now indicated in the Table 3 footnote and referenced in the main text. Ambiguous inequalities (e.g., “<20–30%”) were replaced with mathematically coherent expressions (e.g., “~20–30% of ACV” or “<30% of ACV,” depending on source data). Corresponding narrative statements were aligned with the tabulated values.

 

COMMENT. The conflict-of-interest presentation needs tightening because it intersects with device performance claims. The manuscript says: “The authors thank Gaston Laphitz… (Surgical Franchise, Alcon LATAM), for technical support and valuable information.” Immediately after, it declares: “The authors declare no conflicts of interest.” That combination will raise eyebrows because the paper contains multiple comparative statements favourable to Alcon platforms (e.g., “Centurion… currently represents the most extensively validated system”). Even if there is no financial conflict, the authors should explicitly clarify what “technical support” involves and whether any data or interpretations were influenced by manufacturer input.

Response 12: We clarified that the technical input acknowledged was limited to verification and clarification of publicly available technical specifications for a newly released platform where peer-reviewed literature was limited. No unpublished data, comparative results, funding, honoraria, or interpretive input were provided, and the representative had no role in literature selection, data extraction, interpretation, or manuscript preparation. All comparative statements are based on peer-reviewed publications or explicitly identified manufacturer documents cited as such. The Acknowledgments and Conflicts of Interest sections were revised accordingly.

COMMENT. Finally, the end matter includes template text that should never appear in a submitted manuscript. The “Author Contributions” section begins: “For research articles with multiple authors, a short paragraph outlining each author's individual contributions must be provided… Please turn to the CRediT taxonomy…” That is an instruction to authors from the journal template, not content. Its presence strongly suggests the submission has not been properly edited and will irritate reviewers and editors.

Response 13: The template instruction text was removed. The “Author Contributions” section now contains only the authors’ actual contribution statements, formatted according to the CRediT taxonomy, without any placeholder or instructional content.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All the questions were successfully answered.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The authors responded to all comments and made the necessary changes.